Battery replacement failure issue

[mack2058]

I attempted to replace the battery in my 3rd generation learning thermostat. I ended up being way more difficult than the replacement battery video stated. The battery was really glued to the plate! There were 2 ribbon cables on the circuit board, one very small and one that fed from the bottom and was disconnected when the cover came off.  I reassembled the thermostat and now I have no display but the app allows me to control the thermostat without display. What ribbon cable is not connected correctly? 

[Patrick_Caezza · Accepted solution]

@mack2058 

The Nest Learning Thermostat, 3rd Gen does not have a replaceable battery.

The batteries sold on eBay and other sites are the wrong ones and will cause problems if you try to install one into a 3rd Gen.

[mack2058]

Thanks,

I had to replace the thermostat and have run a 24v transformer wire