Hi,
First thing that comes to mind is check and triple check your jamma wiring, 50 plus wires it's so easy to get a few wrong, we've all done it/still do it.
Is it powering up? Is it getting enough power, if you have a meter test the voltages,I'm using a switching power supply with mine, not PC, which is more normal in a jamma cabinet. Something like this
http://arcadeshop.com/pics/spowers.jpg Voltages can be adjusted, this unit is a bugger for needing it spot on.
You should have 2 dip switches near the black button on the blue unit, just play about with them, there's only 4 combinations.
Even try pushing the black button, in the manual this is the S1 button, that will take you into service menus.
Try plugging a VGA monitor in temporarily to the unit, again, play with the dip switches for this, if you get a display you are half way home.
The unit works off a SD card, try taking it out and putting it in again, mine sometimes needs this helping hand.
one more thing, although you have a wiring diagram with colours for wires, check that against the pins, not all harnesses follow the rules.