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