If you're sure it's the board (not playfield), Rob Anthony can likely fix it for you.

http://lockwhenlit.com/contactus.htm

Shouldn't need to remove the board to narrow it down.

Power off, remove connectors J6 and J7 on driver board, replace F7, power up with coin door closed. If the fuse blows, it's likely a board issue. If it doesn't blow, power off and reconnect J6 and J7 one at a time and see if the fuse blows.

Could still be a bad transistor on driver board.

Power off, J7 disconnected, meter set to diode (tone) mode, negative lead to ground (any driver board screw will work), then touch each of the wires in J7 with positive lead.

If any beep, that's your short. If no beeps, it's likely a shorted transistor on driver board.

Not likely the stepper motor as that's a 12 volt motor.

Power off, remove J6 and J7 connectors, test all pins on J6 for continuity to ground and pin 9 on connector J7.

You need to check continuity between each pin and ground, like you did with the female connector. Not pin to pin.

At this point, I would suggest pulling the board and testing all the transistors for shorts. Q23 and Q25 - Q32 are going to be your suspects.

Nice work. Motor tests may not work unless coin door high power interlock switch is pulled out (or pushed in). On the pulled pad, post a good pic. A stitch will likely get you going again.