After unlocking, – never manually lock without restoring stock firmware, or you may hard-brick the device.
Open the Mi Unlock Tool on your computer and sign in with the same Mi Account used on the phone. How to unlock Bootloader in XIAOMI Mi 8 SE with...
Install the drivers first, then extract the Mi Unlock Tool to a folder (e.g., C:\MiUnlock ). After unlocking, – never manually lock without restoring
Happy flashing