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Just installed C wire; Nest not working

Community Member

My Nest thermostat worked fine for about 3 months, no C wire, then I assume the battery died. I tried charging it up through the USB port but could not get it to charge and startup. So I hired someone to hook up the C wire to the thermostat and my furnace. Right after he did that it displayed that it needed to wait to start up until it charged the battery. It has been flashing red overnight and is still flashing red light and won't start up. I have removed the thermostat and reattached it to the wall, afterwhich I get a couple green and orange lights blinking and the letter G logo but then it goes back to being all black with little light blinking red. Please help!!!


Community Member

How long have you had this thermostat? The fact that it did not even charge when you connected it to a USB seems to point to a bad battery issue. There are links online on how you would go about replacing the battery.

Community Member

I’ve only owned it for about 6 months. It has a rechargeable battery. I don’t think you can replace it. 

Community Specialist
Community Specialist

Hi folks,


Thanks for chiming in, @Whoopsah


@jennberkeley, oh no! We're sorry to hear that. Let's get this sorted out — a few questions:

  1. What type of Nest Thermostat do you have?
  2. When did the situation first occur?
  3. What is the make and model of your heating, ventilation, and air conditioning (HVAC) equipment?
  4. Are the power breakers on, and do you receive power to your home?
  5. Is the thermostat's display seated properly?
  6. Are all the wires of your thermostat seated firmly in its terminals (with no loose or exposed wires)?
  7. Did you use a micro-USB cable in charging the thermostat? 
  8. For how long did you charge the thermostat display? 
  9. Have you checked if any connector pins are bent at the back of the thermostat display? 


Keep us posted.