Suddenly your Ecobee stopped working and it’s won’t turn ON then there might be some technical issues behind this. May be a power source problem is there at your thermostat. If you are having a multimeter tool to test voltage of ecobee between RC and C if it’s less than 24 VAC then that is inadequate to run Ecobee Thermostat.
Troubleshoot Ecobee Thermostat Won’t Turn ON
Ensure the breaker carton to check the circuit which delivering furnace doesn’t get tripped. In case if it’s then turn on back is a way to bring back the power to furnace and then ecobee Thermostat should get power ON.
Might be this issue occurred while rebooting the thermostat when it was performing to give up heat. This may also consequence a whole power loss to Ecobee Thermostat. So, keep this in mind while rebooting ecobee thermostat.
Open furnace to render the furnace control panel which shows you all the thermostat wires that are connected. Mostly devices have 3 purple or 5 orange amp fuses on system board. You need to check this fuse to make sure that it’s undamaged or broken. If you found a blown fuse, you need to replace that. When the blown fuse gets substituted, then your ecobee thermostat will get power ON.
Tripping of float switch go along with by rebooting when ecobee thermostat is at cooling stage this can happen for complete loss of power. You need to look over your float switch, drip pan or condensation pump on furnace. Ensure that there’s not an excess of water or any blockage is there which is putting off the water from tiring. When these things are done, your ecobee will get it ON.