Upon technicians arrival technician was greeted by homeowner. Technician was shown to the thermostat where the thermostat was not coming on. Technician added upstairs to make sure he was getting a 24 V call at the unit. Technician went back to the thermostat to see if the thermostat was getting 24 V technician confirmed thermostat was getting 24 V. Technician tried different thermostat without batteries and it came on immediately. Thermostat unit has failed. Our owner would like to go to Best Buy to buy another thermostat. Thermostat could have internal issues, causing it not to come on home on claim that they have had no power outages in the past month. Homeowners would like the summary to be sent to the email that is listed.