Have you done this sort of thing before?
The next lines are
- Now type the following command to unlock the bootloader:
fastboot flashing unlock_critical
- If the device doesn’t automatically reboot, reboot it. It should now be unlocked.
- Since the device resets completely, you will need to re-enable USB debugging to continue.
I gave a clue about finding the lock status. Ask again if it is not clear. A non-working device like yours will not perform “re-enable USB debugging”.