Just thought I'd jump in here...
I've flashed the TSOPs on 4 xboxes with my matrix using the standard method. Recently I wanted to flash an onboard back to 3944 to install an x2 pro. When doing that, I apparently left t1 grounded, and experienced the same thing turtlesrule described - 1/4th flashed then hang.
So here's the interesting part. My TSOP won't flash (same FF problem as turtlesrule) and my matrix chip won't flash either! When I try to flash it using the programmer, I get the equivalent of the FF problem-- WinLPC says it can't find the device (the red light goes out as soon as it tries to write) and lmilk errors out, not recognizing the device type.
I downloaded the lmilk source and changed it to assume the right device type, to get past the device detection routine and assume the right flash chip config. With that mod it immediately gets stuck while trying to erase. It's the same exact problem as with the TSOP... it always reads FF's and writes seem to fail instantly.
So it seems that making that t1 mistake is unbelievably costly, as it kills your tsop and can kill your matrix as well.
Any tips on how to fix this would be great... I find it hard to believe that a bad flash should irreversibly f*ck up a flashrom, but it certainly seems to. I suspect that there might be some way to hook up voltage to a flashrom to force an erase as well, any flash chip experts care to comment?