We replaced the water heater a few months back and have had issues ever since. The piping is copper to the inlets and they've both been leaking and melting the black rubber gasket for the water heater in both. I've replaced both inlet nibs and gaskets to come home tonight and find the cold side leaking at the fitting. I turned off the beaker and shut off the water to the tank, but a few hours later I smelled electricity coming from inside the closet where the tank was. I found the cold inlet fitting so hot I couldn't touch it and it was bubbling with water. I checked the breaker and found it still off but my bedroom breaker which is a GFI was popped but still in the half position. What the heck is going on?

Time for a plumber or electrician.