I have exactly the same problem........before you start dismantling things try this.
Unlock as usual and open the door wide open, with a screwdriver or something, push the lock mechanism in to simulate the door being locked.
Try unlocking and locking [without closing the door] if it locks now or with the door in a different
position [mine does] might be a break in the wiring where it enters the door.??
There is a switch attached to to lock barrel, it clips on, has an led in the harness with it, presumably to light the lock.