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?
It prompts "Decryption unsuccessful" while installing the firmware. What should I do?
How to unlock Bootloader(BL)?
Can I install the firmware of other phones in my vivo phone?
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?