Long story, knocked a nest thermostat off a customers wall, denting ring, tight turning. Still works fine though. However, bought a new one, drop new one into existing base, no problem all working great. Install old one at my house, and keep getting message "remove and re attach nest to its base" Then, blue circle, blinking yellow/green led, and finally, "nest is shutting down". Regular 4 wire heat and cool system, R,G,W,Y.
Thanks for reaching out. I'm sorry to hear that you're having an issue with your Nest Thermostat. To isolate the issue, inspect the 20-pin connector for any visible damage. Check both the male and female ends on the base and display.