Sorry, but I'm not going to be able to be of any help from here on out, because youre going into "un-tested waters as far as I know...
I haven't seen anyone yet that has put an X-B.I.T 1.0/v1.5 on a v1.6 Xbox yet.... I'm sure it could be done, but I haven't seen or really looked for anyone that has done it yet.
If it is possible to do this (which in theory, it is), then maybe the reason why your still not getting power, is because you have an Xbox V1.6b. They say the 1.6b's have problems with many mods, and can cause some funny things to happen. Maybe you have a 1.6b, or maybe in the process of doing your initial mod; you might have ruined something on your board or chip. Maybe something is just wired wrong, or maybe the X-B.I.T just won't work with any v1.6/1.6b Xbox. I don't really know, and I don't want to keep guessing. All you can hope for is to find someone doing a similar mod as yours, find an article on the web, do some more trial & error, or get some help from someone else on these forms.
Sorry I couldn't be of more help...
Jeepy