The 101B version on the autobuild server is a copy of 101A. This is presumably because it was reported to be compatible, but perhaps it's not. If one as going to work, it would be this version.
Make sure you are using the SD750
(ixus 75) build, not the IXUS 750
(sd 550) build.
If the camera doesn't power on when you have the diskboot in place and the card locked, this generally means that the camera is loading the diskboot, but crashing on startup.
From what I gather this is a common problem with some cameras. I have looked around and noticed other people have had the same problem but I have tried their methods of correcting the problem but I'm still unsuccessful.
If you can link the threads that lead you to this conclusion, it might help us find a pattern.