Restoring Android from a brick state: detailed visual instructions. How to revive a “brick” Android - bringing a “bricked” smartphone back to life

Flashing a phone or tablet yourself is a risky endeavor, especially if the procedure is performed by the user for the first time. As a result of inept actions or software errors, the device may stop turning on, and then you have to look for ways to restore it.

Why could there be a fight?

There are several reasons why the firmware fails:

The update crashed (the phone was disconnected from the computer, the battery was low).
Incorrect firmware version.
User errors when flashing.

Problems after the update can be resolved.

In the worst case, the phone will turn into a “brick”, but even from this state the Android device is restored.

Crash after official update

If you used official tools to update Android, then you can restore your phone after an unsuccessful firmware update using a utility from the manufacturer. Download the necessary software on the company’s website, in the “Support” or “Service” section. In addition, you will need mobile device drivers, which must be installed on your computer.

Connect your phone to your computer.
Find the partition that allows you to perform a restore and roll back the changes you made.

Each manufacturer has its own update program, so look carefully at all items and menus. If you have an LG phone, then in the LG Mobile Support Tool, in the “Advanced Features” section, you will see the “Recovery after an update error” option.

After launching this tool, the utility will download the appropriate version of Android from the Internet and return the phone or tablet to a working state.

Problems after custom firmware

If problems with Android occur after installing custom firmware through Recovery mode, you can restore the phone by updating it again. If you installed the firmware yourself, you should already know how to open Recovery mode. It is usually launched by simultaneously pressing the power button and the volume key.

The Recovery menu is navigated using the volume keys and the power button. If you made a backup of Android before the unsuccessful firmware, then use the “Backup and restore” item to restore the phone to a previously saved state. If there is no backup:

Once the installation is complete, the phone should start working correctly. You can install another firmware version if the first one was unsuccessful - just replace the archive on the SD card and follow the above recommendations.

Firmware reset

If the phone works after re-flashing, it is recommended to reset Android settings to factory state. This procedure will correct any errors that may arise and return the original version of the operating system.

“Scrapping” a tablet or phone is a partial or complete loss of the gadget’s functionality, in which not only the main menu of the device, but also the Recovery mode may stop functioning. A similar situation often happens when installing non-working firmware, accidentally deleting system files, unsuccessfully obtaining chief administrator rights (root access) and in other similar cases.

Recovery methods

To restore a tablet on Android OS from a “bricked” state, you can do the following:

contact the service center;
perform resuscitation at home.

Next, we will consider the second option, since most of the procedures that will be offered to you at the service center can be done independently, while saving a considerable amount of money on the services of a specialist.

Resuscitating the tablet through the standard Recovery menu

If the operating system crashes when loading or the tablet freezes on the Android logo, then everything is not so bad. You can restore a “brick” from this state through the standard recovery environment, which is integrated by default into all versions of the Android OS.

To perform the upcoming work, you need to have on hand a previously created backup of the tablet or a special zipped file with firmware that can be downloaded via the Internet. When choosing firmware, you need to make sure that it is compatible with your device.

Having successfully saved the required archive on your computer, you need to transfer it to your tablet. To do this, remove the built-in memory card from the gadget and connect it to the PC via a card reader. The archive is then copied to the SD card in the root directory. The flash drive can be disconnected from the computer and connected to the tablet.

Once everything is ready, you can proceed directly to resuscitation:

After confirming the above actions, the recovery of the tablet from the “brick” state will begin. After rebooting the gadget everything should work. The only problem is that all information previously saved in the device’s memory (installed applications with settings, notes, SMS, etc.) will be lost forever. To prevent this from happening, periodically make backup copies of your smartphones(tablets) and for greater reliability, additionally save them on your computer’s hard drive.

Restoring a “brick” using CWM Recovery

CWM Recovery (Modrekaveri) is a special program that is installed on the tablet instead of the standard Recovery environment. It fits perfectly with most models of gadgets running the Android OS, and is an indispensable assistant when resuscitating a device from a brick state.

Installation of CWM Recovery

You can install this program either through the standard Android menu or using a personal computer. The first option will not suit us, since the “brick” does not allow us to install anything.

To install Modrekaveri you need:

Install drivers for your tablet on your computer. To find out which driver you need, you can connect the gadget to your PC, then go to “Device Manager” and see the necessary information. After this, the device must be disconnected from the PC.
Get the SP Flash Tool utility. This is a special program that allows you to install custom Recovery on a tablet or phone running Android OS.
Download the recovery-clockwork.img file to your PC, which contains all the information necessary for installing CWM Recovery. For each gadget model there is a specific version of this program. This must be taken into account when searching for a suitable file. For some devices there is both a classic and touch modification of Modrekaveri. Choose the one you like best.
Unzip the downloaded file.
Launch SP Flash Tool.
In the main window, click “Scatter Loading”, and then specify the path to the unzipped Modrekaveri.
Uncheck all the boxes except RECOVERY, and then click on Download.
Connect the tablet to the computer. Attention! Until this time, it must be disconnected from the PC.
The automatic installation of the CWM Recovery program will begin. Upon completion, a green circle will appear on the computer.
Disconnect the device from the PC.

Having completed the installation of Modrekaveri, you can proceed directly to restoring the gadget from its “brick” state.

After incorrect firmware, your phone may become non-functional, or as it is called on the Internet, it will become a “brick”. Then the question arises of how to restore the Android brick yourself. Most sources will advise you to immediately contact the Service Center, but we recommend that you first try all available “resuscitation” options. In this article we will describe all possible options for making a functioning smartphone from a “bricked” Android.

This article was last updated on March 29, 2018.

We completely remove the consequences of unsuccessful firmware

Let's start with the first few steps, which will need to be done one after another. In order not to call Android a “device” and other names, in the future the word “phone” will be used, it’s more convenient and clearer.

Reviving your phone/tablet via Recovery

If the phone is still on, turn it off. Next, hold down the volume button and the power button at the same time. After this procedure, the smartphone will open double recovery menu. Two options will be presented:

Restore the backup (this point is the main requirement for the firmware; if the smartphone was flashed, then the backup was restored). Select the early position of your system, then the backup will start in Backup and Restore.
Chapter Install zip from sd card allows you to start the firmware installation process. At this point you need to specify the exact path to the archive with the firmware. This option deals with system recovery. Especially if the phone was turned off while installing important files.
You may also be interested in the article.

But sometimes when starting the firmware it may not be possible to enter Recovery. Then the situation can only be resolved with the involvement of third-party programs. Typically this application TWRP Manager, ROM Manager or Installer, which are the most popular in this area.

These programs allow you to select all the necessary components for a specific version of the operating system, automatically detecting the gadget and launching Recovery.

If none of these programs helped launch Recovery, then you can try to find a program that can launch it on a specific smartphone model.

Above, we discussed how to restore your Android if it still had a chance of a painless “resurrection.” Now let’s consider what to do with it if the device was completely damaged and became a “brick” that does not function at all. If you think that this process is very complicated, then you should not immediately run to the workshop and pay a specialist, first try to do it yourself. Let's try to fix the situation ourselves at home.

This instruction is based on restoring phones and tablets from Samsung. If you have a different brand of device, then you need to select a different program or choose the option using FlashTool. Having trouble finding the right one? Write to us in the comments - we will help you!

We perform a few simple step-by-step actions:

Install the latest USB drivers for Samsung on your PC;
Download and install the latest version of the program Odin(https://4pda.ru/forum/index.php?showtopic=648344);
Next you will need download official(non-author's) firmware for your model;
Turn off the device, then press “-” on the volume key and “Home”.

After a while a warning will appear.

Press “+” on the volume key, after which the smartphone will enter Odin mode;
Afterwards, we connect it to the computer;
Launch Odin, then press PDA, after which we designate the file in it tar.md5 in the directory in which the firmware is located;
Next, click "Start", we launch the recovery program, after which the smartphone will be ready for use.

In this simple way, we returned the “brick” to its original state of a normal functioning device.

We charge the phone to the maximum so that it does not turn off during recovery (let it stand on charge for a couple of hours);
We take a smartphone that has turned into a real “brick”;
Next, download the official firmware from FTF format;
After which you will need to install the Flashtool program along with the firmware installation files on your computer;
If your antivirus program often complains about other programs, then it is better to disable it for a while so that it does not interrupt the firmware process.

The operation itself to restore Android via Flashtool:

Turn off Android;
Place the FTF file with the firmware at: C:\Users\UserName\.flashTool\firmwares;
After launch, select the correct PC bit depth (32 or 64);
Press the key with lightning logo;
Turn on the “ Flashmode”;
Next, a drop-down window will appear in which you select the available firmware in this program;
At the moment when the firmware is ready, the program itself will inform you that it is time to connect to the PC;
First, the program detects the device and then the Android recovery will begin. After everything is successful, a sign “ Flashing finished”;
After this, you need to disconnect the smartphone from the computer and everything will work.

Video instruction

Answers to your main 4 questions about Android resuscitation

Check the serviceability of the installed drivers, reinstall them if necessary, disable the antivirus. And the most common thing is to check the USB cable and connectors.

The smartphone turned into a brick as a result of a fall, and not due to unsuccessful firmware. Is it possible to save it yourself?

The Android operating system on each individual device has its own system, that is, software components. If it happens that your device has become a “brick,” then it is best to find instructions for a specific smartphone.

Surely many owners of devices operating on the Android platform have heard about the problem of “bricking” a smartphone. And some inexperienced experimenters are familiar with this situation first-hand. What to do in this case? How to get Android out of the “brick” state? These are the questions we will try to answer in today’s material.

Just don’t panic and fall flat on your face – the worst has already happened, so let’s first calmly figure out what it means to “brick” a device. We are talking about a complete (maybe partial) loss of functionality of the gadget as a result of careless intervention in the operating system or incorrect actions in relation to the software.

The main signs of the Android “brick” state

Inability to turn on the device.
There is no response to buttons (physical and on-screen).
The system constantly generates an error indicating problems with the built-in or RAM memory.
When you turn on the device, an error appears about the inability to load the Android operating system.
Other.

In this case, an ordinary user, in a semi-fainting state, will take his Android to a service center where, realizing that a sweet pie has arrived, they will include a far from democratic bill for banal manipulations.

Reasons why a tablet or smartphone gets bricked

The first and, alas, most common is an unsuccessful flashing. Sometimes an inexperienced user suddenly gets tired of his operating system and, having read information from wherever possible, decides to start software modernization of his device. And now the downloading of the latest and most fashionable firmware from who knows what source begins. The result, in general, is predictable - from an imbalance in the system to a complete failure of work.

Conclusion - do not try to reinstall the operating system unnecessarily, and if you decide, do it from verified and trustworthy sources.

The second reason is some kind of failure during the flashing procedure, i.e. interrupted process. For example, they did not pay attention to the battery charge of their device, which ran out at the most inopportune moment (wireless installation method). Draw your own conclusion.

It is not uncommon to roll back to factory software after installing custom firmware.

Various “improvers” designed to increase performance, transfer speed, etc., forced stop of some system applications, even the seemingly harmless installation of a new theme - all these are factors that can bring your gadget to a coma.

How to fix the situation

Standard methods:

First way- we do hard reset(factory reset) via recovery menu(recovery menu). Our actions:

Turn off the device completely, i.e. We take out the battery for a couple of minutes and install it again. Then press and hold the volume key (usually up, but on some devices it can be down). Now you need to press the “home” (or power) key and hold three keys until the “recovery” mode starts. In the menu that appears on the display, select (using the volume rocker) the line “ Wipe Data/Factory Reset»:

We wait until the system completes the reset process and reboots.

Second way– we try to get into recovery mode and flash from there (much safer than using all kinds of software):

And choose Wipe data/factory reset(see above) to delete data. Then you need to select Wipe cache partition. This is necessary in order to erase the partition in this case cache. Now we are trying to install our operating system via install zip from sdcard. To do this, select the archive with the firmware and confirm your choice

To flash the firmware, go to the office. website of the manufacturer of your device. Find the official version of your Android model and strictly follow the instructions.

It is quite possible that your device does not respond to anything at all, including buttons. In this case, you can enter recovery using USB JIG. It’s a cheap gadget, but if you can’t find it, here’s a video for those who are especially handy:

Third way– We try to connect our device to another computer via USB, or replace the cable itself, and then “reflash” it. The fact is that there may have been a lack of power in the PC power supply for the firmware procedure (this, by the way, is a common reason for Android being “bricked”).

Fourth method— restoring the Android “brick” using FlashTool(video):

That's probably all on the topic. If you have had successful experience resuscitating your device, please share it.

Most of the articles in the X-Mobile section are devoted to hacks and tweaks that require obtaining root rights, modifying the firmware, or replacing it with a custom one. However, not every reader is ready to subject their smartphone to such operations, fearing that they can turn the device into a brick or lead to instability in operation. Today I will debunk these myths and show that even in the most stalemate situation, bringing a smartphone back to life is not so difficult.

Destroying myths

Let's talk about what it really means to “turn a smartphone into a brick” and what other pitfalls can await the user on the way to changing the system and installing custom firmware. What glitches can be caught in this case and is it possible to kill a smartphone by reflashing it incorrectly? Will you lose the warranty forever or can the smartphone be returned to its previous condition? Can custom firmware really fail a smartphone owner at the most inopportune moment and are they worth it?

Myth 1. Incorrect flashing can kill a smartphone

A fall from the fifth floor can kill a smartphone, but not flashing it. The main problem that anyone who wants to reflash a smartphone faces is that during the installation of the firmware, a failure may occur, which will lead to its inoperability, and the smartphone will actually turn into a brick.

All this is true, but only on paper. To understand why, it’s enough to understand how the process of flashing a smartphone works and what system components are used. To be able to install third-party firmware on a smartphone, you need to unlock the bootloader (not in all cases), get root and install a custom recovery console (ClockworkMod or TWRP), capable of installing firmware with any digital signature.

The recovery console is stored in a separate partition of the internal NAND memory and is in no way connected with the installed operating system. After installing a modified version of the console, it will be possible to flash custom firmware or even another OS (Firefox OS, for example). If a failure occurs during the installation of the firmware, the smartphone will not be able to boot it, but the recovery console will remain in place, and all you need to do is boot into recovery again and reinstall the firmware.

In addition, any custom recovery console contains a backup/restore function, which allows you to make a backup copy of the main firmware and restore it unchanged (with all applications, settings and data) in the event that something goes wrong. In fact, the smartphone can be returned to its original state.

You may ask: what happens if the installation of the Recovery Console itself fails? Nothing, in this case the situation will be the opposite, when the operating system itself will remain in place, and the console will be lost. To deal with it, you just need to re-flash recovery directly from Android.

Hypothetically, one can imagine a situation where both the firmware and the recovery console are killed (although this is quite difficult to do), but even in this case, the primary bootloader, flashed into the permanent memory of the smartphone, will always remain in place.

Conclusion: it is impossible to kill a smartphone by installing third-party firmware through a custom recovery console. Either the recovery or the primary bootloader will always remain in place.

Myth 2. Custom firmware is unreliable

Firmware differs from firmware. On the vastness of the World Wide Web you can find a huge number of Android builds for every taste and color, and most of them are really slag, which can lead to instability in the operation of the smartphone and loss of some functionality. Therefore, the first thing to remember is that you should only deal with serious custom firmware developed by large teams of experienced developers. First of all, these are CyanogenMod, Paranoid Android, AOKP, OmniROM and MIUI.

Second. There are two types of firmware: officially supported and ported by third-party developers. The same CyanogenMod, for example, has an official version for the Nexus 4 smartphone, but does not have one for the Motorola Defy. But for Defy there is an unofficial port of CyanogenMod 11 from a developer with the nickname Quarx. The difference between them is that the CyanogenMod team is responsible for the support and proper operation of the first, while the second is personally handled by Quarx. Official firmware versions are usually fully functional, but the correct operation of the latter depends on a third-party developer.

Well, third. There are stable and development versions of the firmware. Stable versions of CyanogenMod have the index M (CyanogenMod 11.0 M7, for example). This firmware version usually does not contain bugs. Development versions (in the case of CyanogenMod these are daily nightly builds) may contain bugs and are therefore not recommended for everyday use.

Conclusion: if you install a stable official version of the “normal” firmware on your smartphone, the risk of encountering bugs is minimal. Everything else is for experimenters.

Myth 3. Software that requires root rights can brick a smartphone

In theory, an application with root rights can do anything with the smartphone's firmware, including erasing it completely. Therefore, you need to be extremely careful with such software. The software we talk about on the pages of the magazine is completely safe and tested in our own skin. In addition, for all the time I have been using smartphones on Android (and this is starting from version 1.5), I never I haven’t encountered a situation where software with root support killed a smartphone.

Software distributed through Google Play usually fully corresponds to the stated characteristics, and if it led to a brick or left a backdoor in the depths of the smartphone, it would not last even a week in the store. In any case, here you need to follow the “trust but verify” rule and carefully read the instructions for using root applications.

Myth 4. Root rights make a smartphone vulnerable to viruses

What makes a smartphone vulnerable to viruses is not root rights, but the bugs used to obtain them. Rooting tools and viruses can exploit the same Android vulnerabilities to gain root privileges, so the fact that the device is rooted does not change anything. A well-written virus will not ask for permissions in the standard way, revealing its presence; instead, it will take advantage of the same vulnerability to obtain them covertly.

Moreover, having root, you get the opportunity to install the latest version of Android (in the form of custom firmware), in which these bugs are already fixed. Also, do not forget that most custom firmware allows you to disable root or create white lists of applications that can use these rights.

Myth 5. A rooted smartphone may fail

Software designed to obtain root does four simple things: launches an exploit that allows you to gain root rights in the system, mounts the /system partition in write mode, copies the su binary required to obtain root rights in the future to the /system/xbin directory, and installs the SuperSU or SuperUser application, which will take control whenever any application requests root privileges using su.

None of these steps can crash or kill the smartphone. The only thing that can happen is that the exploit will cause a segmentation fault and the smartphone will reboot, after which it will continue to work normally.

Myth 6. By getting root and installing custom firmware, I will lose the warranty

The guarantee is lost not from the fact of obtaining root, but due to its detection by the service center. Most devices can be unrooted using the Universal Unroot application or by reinstalling the stock firmware using the official application from the manufacturer.

There are, however, two exceptions to this rule. The first is the Knox system that comes pre-installed on new Samsung smartphones and tablets such as the Galaxy S4, S5, Note 3 and Note 10.1. Knox provides an increased level of Android security by responding to any firmware modifications and installation of third-party kernels and firmware. If the user performs these actions, the system sets a trigger that confirms the fact of the modification. The trigger is implemented in hardware (eFuse chip), so it cannot be reset to its initial position. On the other hand, it is not entirely clear whether the service center will refuse to repair the device on this basis. Second: the eFuse chip is installed on some other devices (for example, smartphones from LG), and it also allows you to accurately determine whether the smartphone has been rooted or flashed.

If we talk about custom firmware, everything is more complicated. Typically, the flashing operation requires unlocking the bootloader, and this can be done either using special exploits or using the smartphone manufacturer's web service. In any case, the unlocked bootloader will definitely indicate that the smartphone did not belong to a blonde.

On some smartphones, it is possible to lock the bootloader back, but you should learn about this separately, and also keep in mind that the newly locked bootloader will most likely receive the status Re-locked, and not Locked, as it was originally (this happens on HTC smartphones, For example). The only exceptions here are smartphones and tablets of the Nexus line, the bootloader of which can be locked and unlocked in three clicks without any dancing with a tambourine, and no one will find fault with anything.

INFO

On Linux, ADB and Fastboot can be installed separately from the Android SDK. On Ubuntu: sudo apt-get install android-tools-fastboot. On Fedora: sudo yum install android-tools.

To prevent Knox from interfering with root applications, you can disable it using the following command from the terminal: su pm disable com.sec.knox.seandroid.

conclusions

Getting root and flashing a smartphone are absolutely safe operations that cannot brick the smartphone for purely technical reasons. The only exception is an attempt to hack the bootloader in order to unlock it. In this case, the eFuse chip (if the smartphone has one) may work and block the ability to turn on the smartphone.

Fortunately, today smartphone manufacturers either prefer not to block the ability to turn on a smartphone with a hacked bootloader (by setting a trigger indicating the fact of such an action, as Knox does), or implement a special web service that allows you to painlessly unlock the bootloader with loss of warranty on the smartphone. which saves users from having to risk breaking the bootloader.

Problems that may arise during flashing

So, now let's talk about what problems can arise when getting root and flashing and how to deal with them.

Scenario one: after an unsuccessful flashing, the smartphone stopped booting

Unsuccessful flashing can be caused by several factors: the battery died and the firmware was only half filled; the firmware turned out to be faulty or intended for a different smartphone model. In the end, there was simply not enough space on the smartphone, which can happen when trying to install the latest version of Android on a smartphone that is three or four years old.

Outwardly, all these problems usually manifest themselves either in endless resets of the smartphone to the initial manufacturer logo, or in the so-called boot loop, when the boot animation plays on the screen for more than five to ten minutes. There may also be problems with the screen (multi-colored ripples) and a non-working touch screen, which also prevent the use of the smartphone.

In all these cases, it is enough to do one simple thing: turn off the smartphone by long pressing the power button, then turn it on while holding down the volume down button (some smartphones use a different combination), and after you get into recovery, reinstall the firmware (Install zip from sdcard - > Chooze zip from sdcard) or restore the backup (Backup and restore -> Restore). Everything is easy and simple.

Scenario two: the firmware works, but recovery is not available

This can happen after a failed installation or update of the Recovery Console. The problem is that after rebooting the smartphone and turning it on while holding down the volume down button, a black screen appears, after which the smartphone either resets or freezes.

Solving this problem is not easy, but very simple. You can install the recovery console on the vast majority of smartphones using the TWRP Manager, ROM Manager or ROM Installer applications. They themselves determine the smartphone model, download and flash the required recovery, without requiring a reboot. If you can’t restore the console with their help, just find instructions on the Internet for installing recovery on your device.

Scenario three: neither firmware nor recovery is available

To be honest, it is difficult for me to imagine such a scenario, but, as practice confirms, it is quite real. There are two ways to get out of this situation: use fastboot to upload recovery to your smartphone, or use a tool from the manufacturer to install stock firmware. We'll look at the second method in more detail in the next section, and I'll talk about fastboot here.

Fastboot is a tool that works directly with the primary bootloader of the device and allows you to upload firmware to your smartphone, recovery and unlock the bootloader (in Nexus line devices). Fastboot support is available in many smartphones and tablets, but some manufacturers block the ability to use it. So you will have to consult the Internet about its availability.

To access fastboot, you will need drivers and the Android SDK. When they are installed, open the command line, go to the SDK installation directory, then to the platform-tools directory, turn off the smartphone, turn it on with the volume buttons pressed (both) and connect it using a USB cable to the PC. Next, you need to find the recovery image in .img format for your device and run the command:

$ fastboot flash recovery image.img

Or even force the smartphone to boot recovery without actually installing it:

$ fastboot boot image.img

In the same way you can flash official firmware update:

$ fastboot update update-file.zip

You can find a recovery suitable for your device either on the TWRP website or in the XDA-Developers and w3bsit3-dns.com forums.

We return the smartphone to its original state

In this section, I will talk about ways to return your smartphone to clean stock, no matter what state it is in. These instructions can be used both to unbrick your smartphone and to remove traces of rooting and flashing. Unfortunately, I can’t talk about all possible models, so I’ll focus on the four most popular flagships: Nexus 5 (I call this sample the control one), Galaxy S5, LG G2 and Sony Xperia Z2.

Nexus 5 and other Google phones

Restoring Nexus devices to their original state is easier than any other smartphone or tablet. In fact, it is so simple that there is not even anything to talk about. In fact, all you need to do is install the ADB/fastboot drivers (on Linux you don’t even need them), download the archive with the firmware and run the script. The whole operation looks like this step by step:

from here.
Download and install Android SDK.
Download the archive with the firmware for the desired device from the Google website.
Turn off the device, turn it on with the volume buttons pressed (both) and connect using a USB cable.
Unpack the archive with the firmware and run the flash-all.bat (Windows) or flash-all.sh (Linux) script and wait for the operation to complete.
We launch the command line, go to the directory with the Android SDK, then platfrom-tools and execute the fastboot oem lock command to lock the bootloader.

For those wondering what the script does, here is a list of commands:

Fastboot flash bootloader bootloader-DEVICE-NAME-VERSION.img fastboot reboot-bootloader fastboot flash radio radio-DEVICE-NAME-VERSION.img fastboot reboot-bootloader fastboot flash system system.img fastboot reboot-bootloader fastboot flash userdata userdata.img fastboot flash recovery recovery.img fastboot flash boot boot.img fastboot erase cache fastboot flash cache cache.img

Galaxy S5

With the Galaxy S5 smartphone everything is a little more complicated, but overall quite simple. This time you will need the Samsung Odin application, which will be used to flash the smartphone’s firmware. Sequencing:

Download and install the latest version of Samsung USB drivers from here.
Download and install the latest version of Odin from here.
Go to the website samfirmware.com, enter the SM-G900F model in the search, find the firmware marked Russia, download and unpack.
Turn off the smartphone and turn it on with the Volume Down and Home buttons pressed, wait five seconds until a warning message appears.
Press the volume up button to put the smartphone into Odin mode.
We connect the smartphone using a USB cable.
Launch Odin, press the PDA button and select the file with the extension tar.md5 inside the directory with the unpacked firmware.
Click the Start button in Odin and wait until the firmware process is completed.

As I already said, this operation will return the smartphone to its original state, but will not reset the trigger installed by the Knox system (if it was in the standard firmware). Therefore, the service center may refuse to repair.

LG G2

Restoring the LG G2 to its factory state will also not cause any problems. The number of steps in this process is somewhat larger, but they themselves do not require special preparation and knowledge. So, what to do to return the G2 to factory firmware:

Download and install ADB Driver Installer from here.
Download the official firmware (Europe Open 32G or Europe Open) from here.
Download and install LG Mobile Support Tool, as well as FlashTool (goo.gl/NE26IQ).
Turn off the smartphone, hold down the volume up button and insert the USB cable.
Expand the FlashTool archive and run the UpTestEX.exe file.
In the window that opens, select Select Type -> 3GQCT, Phone Mode -> DIAG, in the Select KDZ file option select the firmware downloaded in the second step.
Click the CSE Flash button at the bottom of the screen.
In the window that opens, click Start.
In the next window, select the country and language and click Ok.
We wait for the firmware to finish, and then turn off and turn on the smartphone.

This is all. But keep in mind that, as in the case of Samsung, the smartphone will still have Rooted status, and this cannot be fixed.

Sony Xperia Z2

Now about how to return the Sony Xperia Z2 smartphone to its factory state. As in the previous two cases, this will require stock firmware and the official firmware utility. You launch the utility on your PC, connect your smartphone using a USB cable and start the update process. Step by step it all looks like this:

Download and install ADB Driver Installer from here.
Reset your smartphone to factory settings.
Download and install the Flash Tool from the official Sony website and the latest firmware from here.
Copy the firmware file to the C:/Flashtool/Firmwares directory.
Turn off the smartphone and turn it on while holding down the Volume Down and Home keys.
We connect the smartphone to the PC using a USB cable and launch the Flash Tool.
Click the button with the lightning icon in the Flash Tool. In the window that opens, select Flashmode, double-click on the firmware in the list that opens.

WARNING

In many smartphones, an unlocked bootloader will not allow an over-the-air update.

In 90% of cases, unlocking the bootloader will entail deleting all data from the smartphone, including the memory card.

conclusions

Flashing a smartphone, and even more so gaining root access, is not at all such a scary and dangerous operation as it may seem at first glance. If you do everything correctly and do not resort to tools that unlock the smartphone’s bootloader, bypassing the manufacturer’s tools, you will not be able to brick your smartphone. Yes, in some cases you will have to tinker to get everything back in place, but what is better - to use a locked smartphone that does not allow you to do even half of the things that it is capable of, or to gain complete control over the device? After all, reinstalling Windows on a PC doesn't scare anyone.