This is why the rebuild boards suck. You can't troubleshoot them very well cause you can't see under them, etc.
Check that all your solder points are perfect (Ie. no cold joints, solder crossing 2 traces, or not connecting a via to the rebuild board). You might need to remove the rebuild board and do it with wires.
What do you get when you try to boot? Does it frag, go to MS dash like there is no mod chip? If it just acts like it is off, then check your D0.