Usually keyboards fail one or two keys at a time. Not all at once. Maybe a key failed in the pressed down position?
They are easy to change though. Gently unsnap the plastic trim strip that's just above the keyboard. Remove a couple screws and the keyboard should lift up and out. There's a ribbon cable underneath with one of the slide open 'zero insertion force' (ZIF) connectors. That's it.
I was never able to find a list of beep codes either.