Don't worry mate, I had the same issue.
See this thread:
https://xdaforums.com/k20-pro/help/destroyed-error-fastboot-locked-t3946012
I got mine fixed, you just need someone with an authorised account to help you out.
You got this far! You are almost there! trust me.
By authorized account, what you mean? because I have miaccount to unlock my bootloader before i relock it again (by mistake)
I tried to flash a global rom using mi flash, and relock ,,, great mistake. the mi unkock says 112 hours remaining to unlock, shoud it work?