checked icracked.com
You might be able to get a new motherboard there.
I just replaced the broken screen on Courtney's phone yesterday - bought the full digitizer display at icracked (second purchase, quality product)
**edit**
I looked at their site, didn't see any pc boards. They've got the cameras, and speakers, and charging ports, and screw sets, and wifi antennas, and … well, most everything but the pc board itself. Figures.