How do I change the batteries in my Honeywell T6 Pro thermostat?

Turn off power by unplugging the furnace from the wall. Gently pull the thermostat off the wall-mounted backplate and remove the old AA batteries. Insert two fresh AA batteries with correct polarity and reattach the thermostat to the wall-mounted plate. The display should light up when complete. If batteries are replaced within two minutes, your time and day settings will remain unchanged.