Agree with smokinHawk with an addendum. Sometimes the fan(s) in the power supply get too dusty and it slows the fan. The fan will then try to go around and draw too much current creating heat. Just another thought. Then the heat will increase which will trip the heat "breaker". Cooling it off and cleaning it off will allow it to reset. This would be the opposite of a thermocoupler. Thermo couplers use heat to keep the fuel going to a source of flame. Thermo couples are used for propane and other natural gas heater units. Very happy that you were able to fix it with minimal troubleshooting.