Truma Control Panel Error -507H: A Comedic Caravan Heating Misadventure

Well. There we were. Unplugged from the national grid.
The place: Te Aroha NZMCA – That’s the New Zealand Motor Caravan Association for the no-movanner, or caravan muggle population.
The time: Very early – like I mean before sparrows-fart early.
The outside temperature: Quite chilly actually – definitely less than absolute zero – bloody cold.