Turned on the switch for electric hot water heater and get warm water. It work great last season.
Did you have to dewinterize before this trip?
My niece had the same problem and they forgot to close the by pass valve during the dewinterizing process thus allowing cold and hot water to mix prior to coming out of the faucet thus the water was just always warm. Once they closed the by pass valve all was back to normal - nice hot water.
Here is a diagram that shows how the valves should be positioned when using the hot water heater. The center valve (by pass valve is closed) so only hot water is coming from the hot water heater. On our 2012 2551 the by pass valve and other two valves are located under the three drawers in the kitchen. You have to remove the bottom drawer to get to the valves. Make sure the water inlet and outlet valves are open and the by pass (center valve) is closed. When the RV is winterized the valves will be put in the opposite configuration (the inlet and outlet valves are closed and the by pass valve is open).
Sue