I have this thermostat in my home. I've recently ran into a low battery issue. I replaced them without reading the directions and I think I messed it up. The display no longer shows anything and the cool setting doesn't work. The only way the fan comes on is if the switch is on the on position. I'm not sure what to do, and the fuse seems to be fine. I was going to unscrew the thing but I don't know what the "w" or "r" screws are... they aren't labeled!
If you have the same thermostat then you can see from the pic that things are labeled RH RC W Y G. Post a picture of you you have if not clear.