Hey there Cowboydad,
Sorry to hear about the issues you're having with your Nest thermostat and the N260 warning, I'm sure it's frustrating, but I'm happy to look into this for you.
The N260 error means that a C wire or Nest Power Connector is recommended for your thermostat.
Since the Nest requires a common wire, you'll have to obtain one or you can try to factory reset the device.
Please let me know if you have any further questions.
Just wanted to hop in here to see if we still needed help on this. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.
Have a great day.