Troubleshoot Nest thermostat e not recognizing base (after long disconnect)

[kenf]

Due to brewing AC problems last year, I disconnected my Nest Thermostat E and wired in a dumb thermostat*.

Later, when the fan self-destructed revealing the probable reason it wasn't starting the AC correctly, I tried to put it back.

I charged up the Nest overnight.  Couldn't find the easy wiring guide online anymore (nest moved all the damn links).  But figured it out and clicked the Nest into the base.

It then acted like I hadn't done so.

I do not have the exact message.  It did prompt for wifi, so I'd gone through that.

That was a few months ago.  The AC's been on since February (and we just had a break this week).  So the wife ain't keen on experimenting as it's hotter than yesterday in Texas.

Any ideas?  I'd hate to buy a new Nest when I only used it for a year and then furloughed it for a year.

[jwlv]

The Nest has a rechargeable battery in it that's most likely dead if it has been sitting around for a year. The normal way that it charges is when the your AC or heater is running. That's when a trickle of power is going through the wires. When your AC or heater is off, there is no power going through the wires, so the Nest cannot charge that way, even if it's connected to the base (the base has no power when the AC/Heater is not running).

What you need to do is take the Nest off the base. In the back of the Nest, there's a USB port. Plug a standard USB cable into that port and charge it up for a few hours. You can use your phone charger. After you're done with that, pop it back on the base and continue setting it up.

Here's a guy on YouTube showing how to charge the Nest with a USB cable.
https://www.youtube.com/watch?v=dLGn1MnOUKg