Is this the first time you've used the rig, or did it suddenly stop providing hot water after being used for some time? If this is the first time you're using it, check the front panel of the water heater to be sure the electric switch is in the on position. Not the one inside the trailer, but outside on the water heater face (first photo). Have you tried running the water heater on propane? The switch for that is on the tank gage monitor panel (second photo). The little red switch on the right side will have an indicator light if the propane operation has been selected. You can run the heater on electric and propane simultaneously if you want fast heating during heavy use.
One other possibility is the controller board for the water heater. Look at the back of it, inside the basement. You should see a small plastic module taped to the back of the tank (third photo, small lt.brown box in center of photo on tank). If the tape lets loose and the module slips, it is possible for the plug to disengage from the module. Replug it, secure it with some real tape (Gorilla) and then try it. Had this happen on our TT after being used on several trips. Took a bit to figure out that was the cause.
Not trying to talk down to you, but I'm not sure of what your experience level with your rig is.
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