Room temp sensor not connecting to t stat via bluetooth

I have two room sensors. 1 brand new and 1 a year old. Both not connecting to my thermostat. I also have a brand new thermostat that is not working. Latest firmware on both, No idea. Tried resetting, battery, factory reset. delete app etc. So annoying. On top of this issue, I have both sensors literally one inch away from each other and they both reading different temps and humidity. hahahah. What a piece of junk