If your original xbox dvd drive is dead, completely, no life at all, this may help you... I have had 2 now (my own 1 and 1 sent to me)
There are 2 small fuses on the drive PCB on the opposite side to the BA chips (look elsewhere to see how to get to em)
they are brown rectangles with the markings "MP200" on them
If either of these is open circuit (burst) replace it with a 200mA fuse. I think i broke mine whilst unplugging the yellow wired connector before the xbox had properly switched off.
worked for me