My Totaline P474-0100 Digital Thermostat is not working it is flashing Fd message

FACTORY DEFAULTS - If, for any reason it is desirable to
Return all stored settings back to the factory default
Settings, press the Mode button. While holding the Mode
Button in, press the Down button for 5 sec. All icons will
Appear. Press and hold in the Fan button until Fd
Appears. This resets all factory settings. To calibrate
Room temperature, press the Mode button once more.
At this point use the Up and Down buttons to calibrate
Room temperature, if needed. Press the Mode button to
Return to normal operation. NOTE CAUTION ON PAGE 1.


Now read and use the rest of your manual. It is all in here.

http://www.rescowh.com/tstats/P474-0100.pdf