Robert, (Garden Grove, CA)
If still no action, leave the thermostat wires shorted together and check for voltage at the printed circuit board. If voltage is present going into the board, it is probably a failed circuit board. The board can be bench tested to determine if it is faulty. Most professional repair facilities will have the board tester. It's also possible the relay in the furnace could be faulty, but we would need the schematic or wiring diagram to fully evaluate that possibility. My guess, though, is that you are experiencing either a voltage/ground problem, (hopefully), or the board is faulty, (hopefully not).