Most cars with power door locks, including the Lincoln LS, use an electronic device called a "lock actuator" to move the lock knob up and down. The actuator uses a mechanical plunger to move the lock that is controlled by the electrical input given off by the lock's switch. Lock actuators can short circuit, but if you have the right tools you should be able to replace the actuator in a couple of hours.
Remove the lock and window switches from the inside of the door with your trim tool. Remove each wiring plug out of each switch.
Remove the car's trim covers located on the door panel using your trim tool. You should see the hex-head door panel retaining screws; remove those as well.
Disconnect the light from the wiring harness on the door and remove the door panel by lifting it up and off.
Find the lock actuator below the lock knob and connected to the lock rod. Unplug the wiring connected to the actuator by hand, unhook the lock rod and remove the bolts attaching the actuator to the door. Remove the actuator from the door.
Insert the new lock actuator into the door in the same position as the previous actuator. Hook the lock rod to the new actuator and bolt the new actuator to the door. Plug the wiring connector into it.
Reinstall the door panel by lifting it down and into position. Re-connect the light from the wiring harness, re-insert the hex-head door panel retaining screws, re-attach the trim covers to the door panel and re-attach the wiring plug to each lock and window switch.
