Sorry to hear about the issues that you're having with your thermostat, I'm sure it's confusing, but I'm happy to look into this for you.
The E105 error means that your Nest Thermostat is not receiving power from your system. I would suggest reviewing this article for troubleshooting steps.
Please let me know if you have any further questions.
Just wanted to jump in here to check to make sure that you saw our response. 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.
It looks like we haven't heard back from the OP so I'm going to go ahead and lock the thread. If you have any further questions or concerns, feel free to create a new thread.
Have a great day,