Maybe someone has encountered this problem with the water heater mostly not working. JSYK, I read all the previous topics but did not find anything similar.
The water heater has worked only twice. The 2 times I pulled into an RV park, and plugged into the external electricity source. Each time it heated the water just fine, got it nice and hot, initially, but did not continue heating the water, even though I stayed in place, hooked up for 2 days each time. So it only heated the water once, each time I pulled into the RV park, and hooked up to external electricity, heated up the tank of water just fine initially, once, but didn't continue heating water. Even though I tried resetting everything to like it was when I pulled in to the park initially.

If this hadn't happened twice, I'd just say the water heater was fried. But twice now, it worked initially, just once, after just connecting to external electricity in both trips to RV parks, heated up the water once, and not again. Until the next park. And never off the generator electricity, just off external electricity, with roof A/C running both time. And even when it's not heating, there is still electricity at the water heater poles, i checked.

I'd hate to spend more money on a new heater AND for someone to diagnose it. So I'm asking here in case anyone ever encountered this. Since it qualifies as a quirk presently, I'm hoping there's a simple answer/solution. Hoping.

Any help is very much appreciated...