Hum water heater not working on either Lp or electric.

See the black rectangular box in the upper left, that is the reset buttons. There you two resets with rubber covers, press them. That could possibly be the problem.

Make sure the water heater isn’t bypassed. You can verify water is in it by pulling up on the pressure refilled valve at the top. Only do that if you’re sure it’s not hot.

Does the water heater work on propane and only 12 volts?
Does the water heater work when plugged into shore power?
Have you checked the 12 volt fuses in the fuse panel?
If you open the water heater compartment are there any burn marks or melting wires?

Can you tell us what you have tried or what you have noticed when you try? Is there a clicking sound when you try to light it on gas?

hum?