First, make sure the phone has unlocked the bootloader, then download the refresh package and copy it to the phone's storage.
Then select \"Developer Options\" in the phone, and then open the \"USB Debug\" and \"OEM Unlock\" options.
Connect your phone to your computer, and then run the ADB command line on your computer.
Enter adb reboot bootloader to restart the phone and enter the bootloader mode. Then enter fastboot flash system package name. zip to load the phone to the system.
Once that's done, restart your phone to enjoy the new system. Pay attention to the backup data and perform this operation with caution.