How to Install an Android OTA Update Without Losing Root
Step 1. When you get notification that there’s an update available for your device, download it but don’t install it.
Step 2. Download and install the latest version of FlashFire beta, it should automatically detect the update file and ask if you want to generate the actions to flash it. Go ahead and click “OK”.
Note : If you’ve a custom recovery like TWRP installed in your Android device, FlashFire will back it up before starting the process, and restore it afterwards.
Step 3. Click the “Flash” button, it will shows a warning that it can take a bit of time for FlashFire to load, and a couple of black screen may appear, go ahead and tap “OK” again.
Step 4. Now FlashFire will reboot and you’ll see a myriad of scrolling text on the display. When it finished, it will reboot again with the update flashed and root restored.
What to do, if Flashing the OTA update will Fail
Download the factory image for your device and copy the image’s.tgz file to your phone’s internal storage or SD card. Open FlashFire and select “Flash firmware package”, a pop up windows will open and select the file you just move into internal storage or SD card.
Now FlashFire will scan the archive to verify its contents, if you’ve a custom recovery and want to keep it that way, simply de-select the “recovery” option. Once you’re ready to flash, just tap the checkmark in the upper right corner. You’ll again be presented with the list of actions before it proceeds as described in the step 2.