Our thermostat quit working and no longer gets power. I bought a new Ecobee thermostat and I'm not confident in which wires go where. Sadly I did not take a picture before I removed it. But I have the units wiring to show.

The brown or T wire was not plugged into the last Thermo but I am not sure if that still applies with the new Ecobee. Any advice would help. Might be a bigger issue than just a bad Thermo but would like to know for sure before the HVAC service come. The old Thermo would run with the battery back up batteries in but not with power from wires any longer if that leads to anything.

If you need to see anything else let me know and I will get the info for you if I can.