At one time the Home app on my phone was displaying status of a Nest thermostat and I could control the thermostat in that app or via the Nest app. Recently though, I tried to access the thermostat from the Home app but the display just spun a circle and never displayed thermostat status or control. I decided to delete the thermostat from the Home app and try to reconnect it. However, deleting device from the Home app also deleted it from Nest app and I could no longer access control of the thermostat from my phone. I reconnected the thermostat on the Nest app, but now I can't reconnect to the device on the Home app. It does not find the thermostat in the "Looking for device " scan; it will not successfully scan the QR code on the device when trying add the device manually, and skipping the the QR scan and entering the setup code leads to a cryptic dead-end page that says "Choose the last 4 characters of your device's serial number" but there is nowhere to enter the characters. How do I get the Home app to connect to the thermostat? My goal is to be able to control the thermostat via voice commands in Google Assistant, but evidentially, this requires that the device be connected in the Home app.
