If I were you, I would call Dometiic and see what they say. It could be in the board, the cable and or the thermostat itself. I would start by resetting all connections on the board and the thermostat. If it happens mostly at night during the cold temperatures you might even have a cold solder joint on the board. Maybe you could find a mobile RV tech that could shed some light on that problem. Otherwise, you probably can only troubleshoot by replacement which means it could be expensive.
Personally, I would start by reseating All connections on the board and the thermostat first.
