Nest thermostat says it has a low battery and won't connect to wifi anymore. Checked the technical info and from what I've read, all numerical values check out that it should be
Amazon.com: CS Cameron Sino 3.70V New Battery for Nest A0013, Learning Thermostat 2nd 3rd Genera, 3rd Gen, T3007ES, T3008US, T4000ES, Thermostat E
Smart Home Battery 380mAh TL284443 for Nest A0013,Learning Thermostat 2nd Generation,3rd Generation,T3007ES,T3008US,Thermostat E
Nest E 1st gen - notification of low battery : r/Nest