I ran into the exact same problem . I rarely use the dryer, but just that one time
I throw duvet and blanket in , did a high temperature drying , stupidly did not clean the lint inside (it was a rush)
but anyways the drying was completed , I took the stuff out, cleaned the lint after, turn off the power. everything was fine
5days later , the power button does not work at all . I checked , it wasn't the breaker , there is power going thru the cord to the PCB .
I opened the back and checked both thermostat, they are fine . No burn mark on any of the PCB either (but I don't really know how to test the PCB without extra one around )