Honeywell Programmable Thermostat Heater "t8001c display work" Questions

...display on Honeywell T8001C Thermostat came back on and working again after I pull the unit off from its base-plate carefully, toggle the switch in the back of the unit a couple of times and back to ...

...display and does not work. I have turned off and on every circuit breaker I have in my house and still not working. I disconnected it from the wall thinking a battery was bad. There is no battery in ...