Nest gen3 issue. Blank screen, flashes yellow/green green.

[Gbotha1]

TRANE Trane XV80 a/c

Knocked a nest off customers wall and dented the ring, making it hard to turn. Bought him a new one, and connected into his existing base. Working fine after setup. Decided to repair old one for myself, and replaced outer ring. The old one now turns on at old location, no problem. When i connect it at my house, with the new base, all i get is a yellow/green flashing light, blank screen. I don't have a spare wire, to connect a C, so I bought the power connector, still exact same problem.
All I get across R and the other wires, or ground is a few mV. At the board in a/c unit. Even the B/C terminal. What am I missing here? I should be getting 24V, right.
Its a basic 4 wire heating/cooling system. R,W,Y,G.
BTW, every time I reconnect my old digital thermostat with batteries, it works fine, heating/cooling.

[Markjosephp]

Hi Gbotha1,

I'm sorry to hear that your Nest thermostat isn't turning on. I'd be happy to take a look into this for you.

It appears that the display is not getting any power from the wires or that the battery itself has been drained. Have a look at this guide to troubleshoot when the Nest thermostat won't turn on.

Please let me know if that helps.

Best regards,

Mark

[Jake]

Hey there,

I wanted to check in and see if you managed to see Mark's post. Please let me know if you have any questions from here. I would be happy to assist, and make sure you are good to go.

Best regards,
Jake

[Jake]

Hey there,

I wanted to check in, and let you know that I will be locking the thread in 24 hours.

Best regards,

Jake