Door on lockdown

I have a 1988 735i. Last week, the front passenger door lock would not lock when the rest of the doors did. My son reached over and manually pushed the lock down. Now, the door will not unlock at all. I've tried the remote, I've tried turning the key in the lock, nothing works. You cannot open that door at all. Is there an override that will allow me to unlock the door, or am I going to have to take the door apart? (I tried disconnecting the negative and then positive battery cables, thinking it would "re-set", but no luck). My son thinks it's cool to sit in the back and be cheuffered, but I need to be able to use the front passenger seat.