Just installed first generation Nest thermostat on my forced air gas system. Old thermostat had two wires connected to W and Rc (Rc was jumpered to R). Set up thermostat and received the "need C wire" message. Upon setup, I receive the error code E294, red wire not connected. I removed and reinserted the red wire, did a factory reset on the thermostat, removed it from my phone and set it up again with the same results. I did this 5 times and on the fifth time it finally worked. The next day, since I had an extra wire, I connected this wire to the "C" terminal on my furnace and on the "C" tab on the thermostat. This too took several tries before it was recognized but eventually, the Nest functioned as designed, motion sensing, connected to both Google and Alexa, etc. The next day it was not working, it displayed the M20 and E298 codes. I've removed the device from my phone and have done about a dozen factory resets, each time with a different error message. One time, all wires not recognized, then E294, red wire not connected, then needs C wire, can't connect to Wi-Fi, M20, E298. Is my Nest defective? I'd also like to check for power but unsure which terminals to test from. Red and C? Sorry for the long post - wanted to give all the details.
