I recently bought a new thermostat at home depot, it is a generic, one size fits all. I followed the directions and connected the proper wires. It didn't seem to turn on after that. So reconnected the old one the way it was and nothing. Then i checked the breaker outside, and nothing. Then went in the attic and opened the access panel on the unit( its a Payne horizontal heat/air, 1989 house) and looked for a fuse somewhere in the unit. Next i tried the self test feature and i got nothing. What could be wrong I checked everything i thought was wrong.