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
No C-wire? Install a Nest thermostat at your own risk – Smart Thermostat Guide
Nest A0013 Learning Thermostat 2nd Genera Learning Replacement Battery: BatteryClerk.com
Nest Thermostat Battery — OneHourSmartHome.com
Nest Thermostat Battery — OneHourSmartHome.com
Nest Learning Thermostat 1st Genera T100577 Replacement Battery: BatteryClerk.com Smart Home