01 driver door lock won't unlock

I have done a search finding similiar threads but no fix.

This is a neighbor's car.

The driver door only will not unlock with the remote or with the key. When using key to unlock and turning to the right key, tension is present on the key and it moves back to the neutral postion without unlocking door. It has been cold (0 degrees and below) until yesterday and today with temps in the 40's. Worked fine ealier today then quite working. Other doors lock and unlock with remote just fine. Is this a BCM problem.

Any advice is greatly appreciated.

When you use the remote, do you here the door try to unlock? There is a little motor the drives the unlock mechanism. You should beable to here it. Since the key doesn't work either, I would say the lock mechanism is frozen. It probably got moisture in it. If you can warm the car up, it may start working.