Installing The Nest Learning Thermostat…… will not turn on after installation

I installed the nest thermostat myself. After taking my old circular thermostat off, I had 2 wires in use (red and white) and a green one tucked away. I first
installed the nest using the green wire that previously wasn’t used, I didn’t need it as the help page above states.
My nest is connecting to the Internet and is now updating.
Now I need to update the other 3 thermostats, perhaps refurbished nests!