You want to update the firmware, as it does not suit you in terms of functionality.
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?
Create a backup copy of user data, contacts and photos and transfer it to your computer.
Insert your SD card into your phone. It must have enough memory to fit the firmware.
Determine your smartphone model.
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
Install the Official TWRP App from the Play Store on your phone.
When you start the application for the first time, you must consent to future manipulations, as well as consent to granting the application Superuser rights. 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 'Select Device', and find 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.
Press the 'FLASH TO RECOVERY' button and confirm your choice.
After the burn process is complete, 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 your phone.
To reboot into recovery, you need to enter the menu accessible by pressing the button with three stripes in the upper left corner of the main screen of the application. Select the 'Reboot' item, and then click on the 'REBOOT RECOVERY' button. The phone will reboot into the recovery environment automatically..
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.
You can start flashing. Click the 'Install' button.
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, you need to check the item 'Zip signature verification', which will avoid using corrupted 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.
When the procedure for installing the firmware is completed, the message 'Successful' appears on the screen.