Before replacing the board again, I'd do a bit of debugging. It seems unlikely that a gummed up hotend or overrunning a stepper axis would kill the controller board logic. It's also unlikely that a brand new board would be faulty. So the fault probably lies elsewhere.
First thing: is there power on your controller board? Is the power LED lit? It could also be that in the gumming up of the hotend, or the ungumming, the heater wires have got shorted out. Try disconnecting the heater wires from the control board. Possibly, if it was shorted out, your power supply is dead. Use a meter to check the voltage on your board.
If you have good power at the board and it's still not recognised, I'd try to check whether the board is communicating with the PC. Try swapping USB cables. Also look at the serial ports as reported by the PC, if you know how. (I'm not at my printer right now, so at the moment I can't walk you through how to check comms).
Get back to me with the results of the power supply check and we can talk about the next step.