Google Nest's battery-drain: Chilly users turn up heat over thermostat software glitch | ZDNet | cloud | Scoop.it
A software update may be the source of Google-owned Nest's smart thermostats becoming unresponsive or incapable of operating efficiently. 

"Nest has since acknowledged the problem, pointing to software version 5.1.3 that may cause devices to become unresponsive or incapable of operating efficiently, in turn causing the device to shut down.

The company has advised users to recharge and restart the device to get it working again as well as provided a nine-step guide to reactivate the device."