A thermostat that seems dead is not always the actual problem

https://josuekmdh775.quillnesty.com/posts/will-a-nest-or-ecobee-work-with-your-salt-lake-city-hvac-system-2

A thermostat that seems dead is not always the actual problem, because control issues can also come from wiring or system-side faults rather than the thermostat itself.