Robert G Haymarket , VA March 28, 2016 Appliance: General Electric Microwave PNM1871SM3SS Ge Microwave Pnm1871sm3ss: No power no nothing on microwave. How to replace Thermostat. Follow the trio ubshooting flow chart inside of the microwave panel - and read articles on this website. Turned out to be a thermostat that had popped and gone bad. Replace the thermostat and it is good to go. 19 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: Less than 15 minutes