How To Remove Thermostat Battery. Open the battery compartment and remove the batteries; Opening the thermostat can vary by manufacturer and model, and you’ll either have to remove a battery compartment or slide the thermostat off the plate holding it to the wall to reveal the spot where the batteries are held.
Remove the nest device from the wall and plug it in using a micro usb. Turn the thermostat off and remove the batteries. Some forums can have meaningful information, while others can be full of fluff.
Remove old batteries and recycle accordingly.
Your thermostat will save the time, schedules and any other settings when replacing batteries. You might have to pull the whole unit from its base to access the battery or remove the front plate to gain access. Those are tricky to find, but any 2.8mm battery should fit if doesn't exceed the size. Remove the thermostat from the wall plate.