I was trying to stay out if this but since no one has mentioned it yet...
A computer power supply is not a guarantee of a successful boot. It's not even guaranteed to have a clean 5v to start a boot. Try this, put everything back in the machine. Only connect j4 on the mpu, turn the machine on and wiggle the j3 connector on the solenoid board. Let us know what happens. If it boots, you have a connector or cold solder problem. If it's still locked, ship it to Barak if he will take it. If it can be salvaged, he can do it.