In case a user’s phone has a bootloader, which has been unlocked, then they can Fastboot commands for the flash factory images.
For those who don’t understand technical terms, they should know that this is the best way to update a rooted device. This is also a good way to fix a bricked phone, and get updates on Android, before anyone else does.
Similar to ADB, Fastboot is a good Android utility, which is powerful and can accept commands with the help of a terminal shell. For those who don’t understand, it won’t be hard if you keep reading the article.
The first thing that the user needs to do is get ADB & Fastboot on their PC. These are the utilities that they need to flash images, with the help of Fastboot commands. There are other three party softwares similar to these two, but they are not recommended because of poor updates. These are official utilities, and are compatible with most new devices.
The user can install Android SDK Tools, which has ADB and Fastboot both, or download the two utilities separately by searching on Google. It doesn’t matter if someone chooses the full package, or just the platform tools.
OEM Unlocking (Step 2)
The next step to flash stock ROM, is to unlock the bootloader of the device that you are using. If you have already done this step beforehand, then you can go to the next step.
In case the user has Android Marshmallow, or a hardware acceleration higher software, then they need to enable Developer options menu on their phone. Once that is done, they can enable OEM unlock, by simply toggling the option.
The next thing that the user should do, is put their phone in bootloader, which happens when switch off your phone. When the screen is black, press the volume down button and the power down button at the same time, for 10 seconds; then, plug a USB data cable in the PC. Wait for a few seconds, and the bootloader menu will appear on the screen.
Now, open the ADB and Fastboot installation on your PC; it would be in the form of directory. Hold the shift button, and then right click on the empty space; from the menu choose “Open command window here”, and then change the directories to platform-tools.
From the ADB shell, the user needs to choose Fastboot Devices, and then hit enter. If you see a series of letters and numbers, followed by fastboot then this means the device is connected.
If it is not, then reconnect it properly, and go to the next step. Unlock the bootloader, by entering the command “fastboot oem unlock” or if you have Marshmallow or a higher version, then “fastboot flashing unlock.” When you receive the query of unlock bootloader, tap on Yes.
Step 6 and 7
Now, you need to download the factory images from the internet and locate the model of your device. Next, extract the factory images, move the content to platform-tools folder, and then open ADB Shell window. Now, you can use the flash-all script, where you just have to type the command “flash-all”, and it would be done.