Hi @FKósa ,
This is not supposed to happen; it sounds like the password was corrupted.
Going from BIOS 62 to 76 is a pretty big jump. I might have suggested that this be done in a couple of steps (i.e. 62 -> 69 -> 76).
I agree with Leon; just to be sure, you should reinstall BIOS 76 using the Recovery Method.
Hope this helps,