Errors periodically appear in the Android operating system.
Some applications will not open.
Many programs from the Play Market do not start.
The phone restarts for no reason.
The phone slows down a lot during operation.
You have decided to try a different version of Android.
Where can I find the firmware?
On the official website of the manufacturer.
On specialized services where users post custom or official OS.
What should be done before installing the firmware?
Back up your phone's user data.
Insert your SD card into your phone. It must have enough memory to fit the firmware.
Find out the exact model of your smartphone.
Charge your phone fully. If the battery runs out during boot, the device will no longer turn on. It will be difficult to restore it.
Find and download the archive with Firmware.
Installing TWRP Recovery
Download the Official TWRP App from the Play Market. And install it.
At the first start, you need to give consent to future manipulations, as well as consent to granting the Superuser rights to the application. Check the checkboxes and press the 'OK' button.
In the next screen, select the item 'TWRP FLASH' and provide the application with root-rights.
On the main screen of the application, click on the 'Select Device' drop-down list, and select your phone model.
After selecting the phone, the program will redirect the user to a web page to download the corresponding image file of the modified recovery environment. Download the proposed *.img file.
When the file is loaded, you need to return to the main screen of the Official TWRP App and press the 'Select a file to flash' button. Select the file downloaded in the previous step.
Click the 'FLASH TO RECOVERY' button and confirm your choice, click 'OK' in the question window.
The recording process is very fast, and upon completion, the message 'Flash Completed Succsessfuly!' appears. Click 'OK'. The TWRP installation procedure can be considered complete.
Copy the required files to the memory card. Using a PC or laptop card reader.
Insert a memory card into the phone.
To reboot into recovery, you need to use a special item in the Official TWRP App menu, accessible by pressing the button with three stripes in the upper left corner of the main screen of the application. Open the menu and select the 'Reboot' item, and then click on the 'REBOOT RECOVERY' button.
Firmware via TWRP
Before flashing, you need to clear the 'Cache' and 'Data' sections, press 'WIPE' on the main screen. This will delete all user data from the device, but avoid a wide range of software errors and other problems.
Press the 'Install' button to start the flashing.
The file selection screen is displayed. At the very top is the 'Storage' button, which allows you to switch between types of memory.
Select the storage to which the files were copied.
Select the firmware file and click on it. A screen opens with a warning about possible negative consequences, as well as the item 'Zip signature verification'. This item should be checked by placing a cross in the check-box, which will avoid using damaged files when writing to the phone's memory sections.
The procedure for writing files to the device's memory will begin, accompanied by the appearance of inscriptions in the log field and the completion of the progress bar.
After completing the installation procedure, a 'Successful' message appears on the screen.