Remove the battery’s on the nest thermostat. With the battery’s out.
Place the thermostat back in the wall base. And it should power up and
start the reboot process.
Remove the battery’s and reinstall to the base. Wait a few min and it
should come on. This should restart the thermostat. Just read this this
on the support page. I have the same issue I’m going to try later. Hope
it works.
