Tech drives to problem call for basement system. Basement system is 13 years old. Previous technician was on site and found thermostat to be failed to which tech replaced thermostat with customer supplied google nest. On arrival thermostat was off the wall. Let customer know that to diagnose thermostat would have to go back on wall. Put google nest on wall and watched system. Thermostat would come on and off multiple times and not receive full power. Found system had an intermittent short on G wire that prevented system from powering on completely. Checked wires and used a different wire from green (orange). Customer agreed to thermostat replacement. Replaced thermostat with EcoBee thermostat and verified operations. Registered thermostat and registered smart sensor. Showed customer how to use thermostat in person and on app. Verified system was operational in heating/cooling and aux heat. 5 year warranty on thermostat and 1 year warranty in labor. Thank you for letting TE CERTIFIED