Blank screen and green flashing light loop with high-pitched buzz on Nest 3

[johnstehlin]

Hi, I'm having the same problem reported on this thread: https://support.google.com/googlenest/thread/19954351/my-nest-thermostat-is-blinking-green-with-a-bl.... My Nest 3 screen is dead. When I charge with a micro USB I get the "G" logo and then a message to plug it into the wall. When I plug it into the wall it goes into a loop of one flashing red light, then a flashing green light, then quickly to orange, then solid green briefly before restarting the loop. During the loop there is a high-pitched buzz.

Following the previous thread, I've plugged the Nest into my computer and have located the .plist file. At this stage, previous troubleshooters have messaged users privately for further instructions. How should I proceed?

[Geoff103]

Ssme problem here.

Please advise 

[GarrettDS]

Hey there, 

So sorry to hear about the issues with your thermostat, I know it can be confusing, but I'm happy to look into this for you. 

I would suggest running through these troubleshooting steps first to see if you can solve the issue here. 

1. Check that the display is properly connected to the base

If the display isn’t fully seated on the base, your thermostat won’t turn on and can’t charge its battery.

1. Pull the thermostat display straight off the base.
2. Make sure that there aren’t any cables sticking out from the wall that might prevent the display from being fully seated. If there are, press them back into the wall.
3. Line up the display and base connectors and press the display straight onto the base until you hear it click into place.
4. If your thermostat shows you a blinking red light, the battery is charging and it will eventually turn on. It can take up to an hour if the battery is severely depleted.

2. Check that your system is receiving power

1. Try turning the breaker or switch that controls power to your system back off and on again. Make sure the switch is pushed all the way to the On position.
2. If you have a fuse box, check that the fuse controlling power to your system isn’t blown and is working normally. Replace it if needed.
3. If your thermostat shows you a blinking red light, the battery is charging and it will eventually turn on. It can take up to an hour if the battery is severely depleted.

3. Check your thermostat’s wiring

Symptoms caused by wiring issues usually occur when you're first installing your thermostat. 

Important: Turn power to your system off at the system switch or fuse box. This helps protect your system and thermostat from possible damage.

Check that each wire is fully inserted into the base and is corrosion free.

4. Check if your Nest thermostat is damaged

In rare cases, a Nest thermostat can be damaged by things such as a power surge from your system, connecting it to an incompatible system, or by touching exposed wires together if power to the system hasn’t been turned off during installation.

You can test for this one of two ways.

Try reinstalling your old thermostat

If your system works as it should with your old thermostat, your Nest thermostat may be damaged and needs to be replaced.

1. Turn off power to your system at the breaker box or system switch. This will help protect your system and your thermostat from possible damage.
2. Pull your Nest thermostat off the base and take a picture of the wires for reference. 
   Note: If you still have it, use the picture of the wires in your old thermostat that you were instructed to take during thermostat installation .
3. Uninstall your Nest thermostat and reinstall your old thermostat. Make sure that the wires are placed in the right connectors.
4. Turn the power to your system back on and test that it’s working properly.
   • If your system works with your old thermostat, try getting a professional to install your Nest thermostat. To get a professional to help install and set up your Nest products, contact our installation partner, OnTech. If your Nest thermostat is damaged, or if you need a professional to service your system, the installer may let you know.
   • If your heating and cooling system doesn’t work with your old thermostat either, there is probably an issue with your heating and cooling system. It could be a blown fuse on the furnace or a bad circuit breaker, and we’d recommend for you to contact a local pro.

1. Pull the thermostat display off the base. 
2. Pull out one wire and inspect it.
   • The exposed part of the wire should be clean, straight, and 3/8” (1 cm) long. Cut and re-strip any crooked or corroded wire ends.
3. Re-insert the wire. The connector button should stay down. If it’s not, the wire isn’t fully inserted. Repeat the above steps with each wire.
4. Once you've checked all the wires, push the display onto the base until you hear a click.
5. Turn the system power back on.
   • If your thermostat shows you a blinking red light, the battery is charging and it will eventually turn on. It can take up to an hour if the battery is severely depleted.
   • If you don’t see a blinking red light, it's possible that you’ve put wires into the wrong thermostat connectors. Make sure you have entered your system’s wires correctly into the Nest app and follow the wiring diagram it gives you.

If these troubleshooting steps did not work please let us know so I can create a case for you.

Best regards, 
Garrett DS

[Geoff103]

Thanks for your reply.

However, all check got me nowhere and it was obvioous that the Nest had developed a fault.  Google Support resisted for a long time (5 hours on the phone) but finally acceoted my request for a replacement under warranty.

Replacement head unit works perfectly, confirming my diagnosis, which I suspect Google Support would still dute if I hadn't persisted.

[GarrettDS]

Hey there, 

Glad to hear that you got a replacement. Since we have come to a solution I'm going to be locking this thread. If you have any other concerns or questions, please feel free to create a new thread. 

Have a great day. 

Garrett DS