This just happened, and I'm not too mechanically inclined, so any help would be appreciated:

My rear driver-side door's lock just stopped functioning. It is in the locked position and I can't put it in the unlocked position using the key or manually (and I've tried using a LOT of force). The door itself is actually not locked. When I lock and unlock the doors, all the other doors work fine, and the broken one tries to lock and unlock, but it is stuck hard in it's position. But, the door stays unlocked under all circumstances.

Any ideas on where I should start?

 

Try unlocking with the handle pulled. Otherwise you may need to remove the interior door pannel to access the latch mechanism.

Here is a similar post that recommends having a locksmith try using a slim jim to reach the latch mechanism.

https://www.clublexus.com/forums/rx-...ly-locked.html

 

I saw this online for a VW but see if thats something useful

 

The above video offers no benefit in this situation unfortunately.

Your issue is that your door actuator has stopped functioning properly and it no longer allows the cable attached to the locking mechanism to function properly.

Replace the door lock actuator. Problem will be solved. It's easier to fix than most may think.

 

Doors are supposed to lock automatically at 20 speeds
But the doors did not close
It seems to be a malfunction in the programming system.These faults occurred immediately after the battery change.
Do you know how door locks are programmed like factory reset?

 

 

When the latch is raised upward, the actuator connects the car's door handle to the aperture. The door handle and the unlock mechanism disengage when the latch is pulled downward, preventing the car door from opening.