Today's issue of the RVTravel.com newsletter had an interesting article. There is a company called Dinosaur Electronics that builds replacement control boards for a great many RV appliances (refrigerator, water heater, furnace, and so forth). Since OEM control boards may be hard or impossible to find, this might be a good source, especially if the alternative is buying a whole new appliance.
I've had no contact with them (thank goodness), but if someone here does, perhaps he/she could report the experience.
www.dinosaurelectronics.com/
Bill