To get the heater working again, press the red reset button on the thermostat.Then after it is getting hot, you can test it to see if the thermostat is defective, (unlikely), or the element has burned out (probably).: Recently our hot water got extremely hot (about 175 degrees). The next morning we hardly had any hot water. I was told it was probably the thermostat and possibly a heating element as well. Is a thermostat a simple repair that I can do myself? I have a Kenmore water heater.