How to flash the firmware?
Can I downgrade my phone to the lower Android version?
How to downgrade my phone?
Where can I download ROM or firmware for my phone?
Can I install the firmware of other phones in my vivo phone?
It prompts "Decryption unsuccessful" while installing the firmware. What should I do?
How to unlock Bootloader(BL)?
How to access Recovery mode?
How to exit the Fastboot mode?
Is there an international firmware for the phones such as X21 sold in Chinese Mainland?