only thing I can think of is check ebay (or even the ys section here) for "non-working" ones being offered up. Thinking if you came across a working (used) motherboard going for cheap, that might be easier than trying to actually repair it (but then again, it may not for all I know).
I've opened up mine before to do the CF mod to it, I'd have to think that replacing a m/b in one of those can't be all that bad.....