This happened after I got back from travelling, I was gone for 3 weeks so I disconnected the car battery and locked the car manually. Problem started when I get back and try to unlock the car using the key. It's turning but the door is not unlocking. I try using the service key with same result. Finally I called a locksmith. He couldn't get the driver side lock to move as it's too stiff and finally unlocks the vehicle through rear passenger door.

Once battery is hooked up, the car doors locks and unlocks through the fob key press, but not through the key. If I try to move the driver side lock manually it has a lot of resistance and doesn't move. Other doors doesn't have the same issue.

Currently I'm keeping the driver door open as I don't want to depend on the key fob. When driving the door get auto locked and then unlocks once engine is turned off. One thing I'm worried is that the moving part of the lock is still getting used, whether the problem will increase until it stops working at all.

Trying to understand what could be the issue.