telling someone to fill in the lpcs (in most cases) isn't going to fix a Flash Red And Green.
There are a few things that could be wrong here.
If it is easy to do so, remove your mod from the LPC (hopefully you have a pin header installed) also disconnect D0 for the time being. If the xbox still works then you know you havn't killed the motherboard. If it does... check all the areas you've been soldering in for broken traces (especially d0 -use your multimeter around top and bottom points to check continuity) and solder splashes.
You may want to check all your points, resolder your lpc points (i guess filling them in could possibly fix a bad soldering job...), and tripple check your d0 point.
If you're still getting a FRAG, then try placing the chip in the box that's working (and vice versa)... if it's still not booting you may have a bad bios... although this probably isn't the case.
and there's always the chance that the chips bad, also unlikely.
If it's a bad bios, you can try swapping the chips while the box is booted from the good chip, then attempt to flash a bios image to one of the banks.