Hello again Al, I'm sorry it took so long to respond. I was away for the weekend.
It sounds like you have a volt meter so let's diagnose the system with that and a few logical steps as well. From your explanation of the symptoms, it sounds like it's either a shorted reversing valve solenoid, a defrost board that's failed or both. It sounds like you have your thermostat wired up right now with the reversing valve wire to B.
I would first disconnect the reversing valve itself from the defrost control board, I'm referring to the 'output' side of the defrost board, not the B wire thermostat connection to the 'input' side of the defrost board. Then ensure you have a good fuse in the air handler and turn power back on. Put the system in heat and measure the voltage at the outdoor unit from C to B at the defrost board. You should have ~24 volts ac. Now measure from C to the 'output' side of the defrost board reversing valve connection, you should have ~24vac there as well. If those checks pass, your defrost board is fine, if the checks don't pass, you have a failed defrost board.
Now with power off to the system and the two reversing valve coil wires disconnected, you should measure the resistance between the two reversing valve wires with your meter set to its lowest resistance scale (Rx200, Rx400 etc..). Let me know what you find. Alternatively, if the defrost board showed failed in the voltage check above, you could bypass the defrost board reversing valve relay by disconnecting the thermostat B connection and connecting it directly to the reversing valve coil wire that was on the output side of the defrost board. The other reversing valve coil wire should be connected to 24 volts common somewhere in the the circuit. If you can give me the model number of the outdoor unit, I can give more specific instructions. When you bypass the defrost board to reversing valve coil, turn all power back on and see if the fuse blows. If it does, you have a shorted reversing valve coil and will need to replace it. If the fuse doesn't blow and the system goes in to heat, you just have a failed defrost board.
Let me know how that goes and we'll go from there.