2006 Grand Prix drivers door lock won't lock when car started and in gear or using door switch from inside vehicle. Rest of front and rear doors lock lock fine. Drivers door only locks if stem manually pushed down. Unlocks OK using door switch. Key FOB w/remote start is not working due to bad solder connections.

Any ideas on what might be wrong? If door lock actuator needs replaced how do you get the door panel off to access it. Or could it be BCM module?

Thanks.