I was working on one that did the same thing. A cust of mine used a limit on top of the heater that was not exactly like the original. Sometimes getting the exact replacement is the better way. The terminals of the generic rubbed up against the frame and shorted out. Also the clip that holds the small limit to the side of the heater housing can get shorted quick if you didn't look real close at that long screw as it was going into place. In that case it would be dead as a doornail. I know from experience.