Came out to call. Customers son stated that the system wasn’t operating properly. They lost power this week and it came back on yesterday. When they tried to kick the system on the thermostat was blank. I checked system over and found 3 amp fuse blown. I replaced fuse and rechecked system. Thermostat was lit up, but was not allowing me to turn anything on. I bypassed the thermostat to test and verify the system would turn on and to pin point the thermostat as the issue, and it is. I discussed with customer about repair needed and pricing. Customers son will replace the thermostat. I made customer aware that there will be another service fee if I have to come back out.