Are you sure they're dedicated KI PCBs and not KI2? From the pic you posted, it looks like your U96 has 20351 (KI2) instead of 19489 (KI).
This only works on dedicated KI PCBs, because the dedicated KI2 PCBs remapped several addresses (and running the wrong one does exactly what you're seeing, going into test mode and locking up). You should confirm that your test switch isn't thrown as well, since that would do the same thing ("DISK TEST SKIPPED"), except you'd be able to run the diagnostic tests.
Did you try burning the "Killer Instinct 2 (Conversion) U98 Any-IDE Boot ROM L1.4" ROM without my patch? That shouldn't work with the conversion PCBs either on that board though... yours should require the "Killer Instinct 2 (Dedicated) U98 Any-IDE Boot ROM L1.4".
BTW, I just re-tested, and it boots fine for me on my KI PCB.
Edit: I just looked more closely at the pic you posted - your "working" ROM says KI2 ANY-IDE DEDICATED BOOT ROM. So that's correct, this ROM won't work with your board, but you also don't need the conversion PCB (it'll work if you plug your drive directly into the PCB). Your board can only run KI2 though (there's no KI ROM to run on dedicated KI2 hardware).
DogP