Truma AquaGo water heater has a few different modes. If the various settings (ECO, COMFORT, etc.) are not available via your Truma controller, the Truma controller was probably powered up the first time with the truma heater itself powered off and/or no water in it and/or propane valve not open. With water heater powered on, water and propane available, you may simply need to reset the factory settings and then it will do a one-time "learn" of what is connected to it (how water heater and cabin heater). Once learned, they will be saved and you won't have to do that learning procedure again. (For awareness, I'm not 100% sure if that is the case if one disconnects the battery completely. Something to be aware of if one disconnects the battery completely, then reconnects and discovers the Truma water heater features are missing from the control panel when you power the water heater up again). Once the controller learns what is active, functioning and connected to it, your controller will then give you access to the hot water heater settings.
I had the same issue with my camper when I first took delivery and it was an embarrassing long time before I figured that out why it would only function in eco mode. At first, I thought OEV had only sourced the the economical "AquaGo Basic" water heater model, but others of that year confirmed they had the "AuqaGo Comfort" controllable one. I did find a work around at first. The owners manual mentioned the power switch direction on the water heater has two "on" positions and they function the same, but for my unit, before I reset the Truma controller, I noted that if I flipped to the up "on" position, it powered on in ECO mode and if I flipped the power switch to the down "on" position, the water heater powered on in "COMFORT" mode. I keep that nugget in the back of my mind in case the Truma controller ever fails or is damaged. In any case, once I read up and suspected the Truma controller simply had never been allowed to "learn" the Truma water heater was there, I reset the controller with the hot water heater powered on and filled with water and propane on and it learned it was there. After that, I had access to all the features via the control panel.
It is an on demand system but still uses a small tank to buffer and be "ready". Maybe a liter or so. Compared to 3 or 5 gallons of a typical camper water heater. The mode impact stand-by and on demand water temps. In ECO mode, it is still on demand, but keeps the water temp at 41F/5C. Basically, antifreeze mode while operating on propane (but not to be confused with the true "ANTIFREEZE" setting which requires the 12v DC electric antifreeze kit). In ECO mode, as soon as hot water is called for, it the AquaGo fires up and heats the water to 120F/49C, but it takes much longer to come up to full temp and wastes a lot of water. In "COMFORT Mode", the water is kept at the ready at 102F/39C and when called for, bumps that temp up to a default of 120F/49C so the fully hot water comes almost immediately (run just enough water to get water from the heater to the open fixture). I believe one has the option to control/adjust the output water temperature as well. The heater does cycle off and goes back into its ECO or COMFORT standby temp when water flow is below .4 gallons/min. but even then, in COMFORT mode, the temp will stay above 102F/39C so is usable.
Sorry to hear on the maxxair damage. It was the frame itself and not the vent?
My previous camper's fan did not have a locking fan vent. Same on my current enclosed trailer. Both would work their way up on bumpy roads or high wind. I'd arrive and my vent would be open. Thought I forgot it but after tests, proved it was working it's way open on it's own in certain situations.
Now, my particular CAMP-X fan vents can lock (once black knob is used to crank it close, that same knob can be pushed up to lock the know from turning on it's own). Is your fan vent have the same knob that can lock? Do you think the frame can be repaired (epoxy) or remove and move fan/motor etc. to new frame? Hopefully don't need to replace the entire fan.