HOW do I get nest to turn on after it said it needed more power

[ReitM]

Unit has basically turned itself off and cannot be revised.  Says it needs to shut down to save power to the battery and now it's completely dead.  For months the Iphone hasn't been connected yet the online ap has been working.  

It is COLD and this just happened a few hours ago.  Anybody know how to get the nest to turn on?

My thermostat Model Nest Learning Thermostat Display (3rd Generation) Backplate model Backplate-5.4

[Mace67 · Accepted solution]

Sounds like you don't have a common wire on C terminal.  A NEST needs a common wire or you get these issues. The common wire creates a circuit to furnace where the furnace supplies 24volts to thermostat at all times.  Without a common wire it relies on internal battery which will eventually drain it down.

To see if it's got a common hooked up go to the section where it checks wiring and see if it recognizes it. You can also pull stat off it's base and the wiring will be visible 

[ReitM]

Thank you it was the furnace which had no connection.  Your solution was helpful even though I just saw it the next morning.