Q. I have a first generation Nest thermostat, model 01A. It stopped working and has a blinking red light, indicating a power problem. As recommended by the troubleshooting guide, I removed it and charged it via the USB port. It did not fix the problem. I have the same thermostat hooked up to a separate HVAC system downstairs, so I pulled it off the back plate and tried it with the upstairs system. It worked, so the problem is with the thermostat and not the HVAC system. Is it fixable? I really do not want to pay for a new thermostat and installation.
—J.M., Fredericktown, Ohio
A. Nest says the first generation thermostat battery is not replaceable. Despite this, there are multiple online vendors offering replacement batteries for under $20. The user reviews are very poor, complaining of fragile connectors, an unwillingness to charge and bulges in the battery case that prevent a proper fit.
