If the light had two wires to it then the ground for the light is routed down and through a contact switch in the door jamb swhich goes to ground when the door is open. It is possible that they put a screw through the ground wire so the light thinks the door is open. This also makes me think that they might have hit the hot wire on one attempt and blew the fuse, second attempt missed the hot wire and hit the ground. Also see if you can take the light down and check the mounting screws to make sure they havent pinched or penetrated the wires. (the easiest way to start checking. Beyond that they might have to pull the headliner back enough to check the wires.