Trying to get cover off to check wiring due to no lights working but still hear clicking sounds of unit turning them off 4 minutes after closing door. Replaced bulbs - no change. Four screws removed but cover still stays on. Stopped working when main sprocket for chain snapped. Repair company replaced sproket but said I need to look at wiring to get lights working and then they left. I wasn't home when they were here so wasn't too pleased.