trouble with a PSAudio p300

I've done some modifications on a P300, which can be seen here:
http://homepage.mac.com/theo224/57483957/PhotoAlbum52.html
Please allow me to ask for help.

The unit was working fine, but in listening to differences between op-amps on the MW2 card, I accidently put a module in upside down. The unit will power up without blowing fuse, but no output, and the display reads the red light in lower corner.

I'm not an electrical engineer, and this is my first DIY project, so I don't have much knowledge or understanding of circuits. I'm guessing a shorted op-amp, but when I use the diode/transistor test with a multi-meter: black at -Vin, red at Vout = .887V; black at +Vin, red at Vout = .886; this with both modules.

[IMGHTTPDEAD]http://homepage.mac.com/theo224/.Pictures/Slide%20Shows/Public/modification%20project/IMG_0004.jpg[/IMGHTTPDEAD]

The other transistors seem okay too, but I will check again.

Are there any suggestions?