Unlock MI A1 Bootloader without using "Enable OEM Unlock" option


My problem is that my phone is stuck on mi logo and I can’t enable oem unlock option through developer mode as I am not able to get into the phone. And when I try to do through in command prompt by opening it in adb , it gives the error “oem unlock is not allowed”.

1-So in this case , what is the solution to unlock the bootloader in order the flash ROM on my mi a1 . My phone is stuck on mi a1 logo and without unlocking the bootloader, I am not being able to flash the ROM .

2- Also any idea if I can take a data backup in such a condition? Post that I can go to service center and they could install the software again from scratch but this would delete my existing data and I don’t want to lose that so I want to take a backup before that .