Both of those voltages should have worked.
It doesn't need any of the data lines to work standalone in the IFU, so it's either not getting power or ground, we should note that there is a few components in the CD-ROM2 also, it's like a diod, since it's comes from both the DC socket and the CD connector, and it goes into one just being separated with a diod, maybe something more, wolfman on the forum had some trouble with that 2-3 years ago and we checked everything around that back then. So it might work with the DC power but not the the CD connector.....