well, the disk drive is also part of the system, it also can produce shortcuts if wrong soldered.
try clean the DD connections and try again, if you are having to much problems with the mobo, and not power on anymore, try getting another cube for replacement.
my advice is: go slowly but secure, check everything at least twice times before perform the functionality test after made progress, perform lot of functionality tests per each new steep you do, it can help to fix problems and detect where is the problem.
and, dont get frustrated, gamecube is a bit hard hardware to start, but it can be dont with patience and with some tricks.
if you got to much estresed, rest for a day or two, and continue then, get extra gamecube parts for replacements allways is good.
good luck mate, I wish you acomplish your project, just let me know if I can help with something
