I'm assuming you've already done this but just in case; go back over every connector very carefully and inspect that they are installed in the proper place and that nothing is off by a pin. If that doesn't fix it see the WPC95 sections here: http://techniek.flipperwinkel.nl/wpc/index3.htm#poweron that relate to the LED states, sounds, etc. for the CPU, A/V and Driver boards. You may also want to try to start it up with the A/V board disconnected since you know you had it incorrectly connected before.

no need to post a picture of the coindoor, the boards in the backbox is what matters

Try to start the game with the 2 flatcables on top of the cpu board (far left board) disconnected.
If it boots then, double check they're plugged in correctly.

I don't think you have NVRAM installed. Looks like it might be stuck in default settings. If so, then what happens if you install batteries? If the same thing occurs, unplug the ribbon cables from the MPU to see if the MPU boots up by itself and then plug the ribbon cables back in.

If the DMD is not on might because you are missing the DMD power connection at the top right on the A/V (top right) board.

looks like the blanking led is stuck on ( top one on cpu ) this should come on at power up then go off and the diag ( center led ) should start blinking.

Most likely the short grey ribbon cable between the MPU and power driver board is one pin/row off correct alignment or not making proper contact.

Excellent. That is my favorite mod. Do you show "Factory Settings" on the ColorDMD when you turn the game on?

That's also what I saw in that picture - therefor my suggestion of trying with flatcables disconnected.
If his cpu doesn't boot then nothing will show on the dmd either

First he should check is if it boots then with all cables on the cpu disconnected (except for power : connector with with grey/black wires)

If you removed the head then the only cable you pulled from the CPU would be the matrix cables at the bottom. Pull and reinstall all cables in the head you removed.

I have no idea why folks are even talking about the DMD when the game is obviously stuck in reset based solely on the single picture of the CPU board that shows the blanking circuit is activated.

So far the only good advice I've seen is to remove the ribbon cables from the CPU to see if it can complete the boot cycle as failures on other boards can cause the blanking circuit to activate as a protective measure.