Nest Thermostat 3 Gen Green Blink and Not Working

[Adrianmanse]

Hi,

the thermostat isn’t working so no hot water / heating.

Green light is flashing with black screen and is making an odd buzzing type sound.
i have unplugged and plugged in and nothing changes. When I plug the power directly into the thermostat at the back the home icon comes on and it tells me to plug into the dock. But when I do that it is just as before. 
I have tried holding the main button for 10 seconds but nothing.
any suggestions please??

[Frustratedddd]

I assume the buzzing noise is coming from the display, like a clicking? New battery required if that's the sound, most of the time.

[Adrianmanse]

Thanks. I have ordered a new battery. 
appreciate the support. 

[Frustratedddd]

Yes with a clicking/buzzing noise, it's usually the battery not having enough power to kick the display into action. With luck that should help, cross fingers. When changed, plug the USB into the display for an hour or so before fixing to the base.