I had this happen yesterday. It was a hot PM in a vacant condo. There are wall-mounted electric fan heaters in every room. I noticed one digital thermostat was blank, but then a little while later it was lit up and giving the room temp 24 C. I ran the heat up to 26.5 C, and went somewhere, came back, checked the heater, yep it was warming up. Went to turn off the heat. Display was now blank, heat stuck on. [] About 15 mins later, the room temp was 26.5 C and the display was back, so I turned the stinkin thing down and went for a tour of the garage. []