DVD drive replacement - noon needs to get educated

So my original Xbox 360 died a couple of weeks ago but I was able to score a replacement from a friend that had one with a broken dvd drive.

My old Xbox DVD drive is a liteon DG-16D2S.
The replacement Xbox drive (broken) is a liteone DG-16D2S-09C

I went ahead and took everything apart and installed the PCB from the broken DG-16D2S-09C into my working DG-16D2S drive.

Booted the Xbox and it appears to be working but the drive doesn't appear to be reading discs.
Now I've had issues with my DVD drive taking 15-20min to properly recognize game discs when my Xbox was still working so I'm wondering if my drive my also be having issues.

Otherwise I'm wondering if this could potentially be a firmware issue and how to possibly get this fixed.
old good drive is HW a0a1. the defective one is a0a2.
fw are also different, a0a2 is fw 74...

I'm also considering reverting back if I can figure out why the deffective unit won't eject the disc (they get hung somewhere in the tray... from what I've been told that may be all that's wrong with that drive).

Any help would be appreciated.