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Did you install Bitlocker on the computer, as an add-on ?
Do you want to disable Bitlocker, then? that may be needed, to get rid of the initial prompt.
Turning it Off in most cases and situations requires that you know the password.
Do you know the Bitlocker password?
Have you ever entered anything in response to the prompt?
It is an encryption software that can if need be, scramble or encrypt your whole hard drive.
Try doing this, if you like, on your laptop:
manage-bde -unlock C: -RecoveryPassword *****
Does that look impossible to do, to you?
I wish to state that I have no access to your Surface 3 whatsoever at this point. I am limited completely to advising you.