One trick I have used on water heaters is to open the door and remove one of the top outer seam mounting screws. Then drill a slightly larger matching hole thru the door at the same location as this seam hole. Then use the same screw to go thru the door and into the mounting hole to secure the door. This is an additional door lock in case the main door lock breaks and prevents the door from coming open during travel, etc.
Jim and Connie w/3 lb. Chihuahua= Nugget
2016 Rockwood Ultra-Lite 2608WS
2004 Dodge Ram 2500