not my forte, but from my research so far, sounds like a weak laser problem, especially so if the drive no longer recognizes your originals. you may need to recalibrate your laser.
Hey guys. So I have an old ass 360 I'm trying to update. My original drive is a Hitachi 79. It stopped opening for me, but the laser noticed when I put a disc in it, so I know the laser was fine. I ordered a new Hitachi and got a 78, (even though I requested a 79..oh well I guess.) put my old pcb in it and my assumption that it was fried was confirmed. So I went ahead and flashed the new drive with the old key and the fw, no problem.
Now my issue is that the drive is not noticing dvds, cds or any other media when I put it in my xbox. As a side note, I have kept my xbox out of the shell (case) to make it easier to test. Does anyone have any clues as to why dvds aren't being seen on either drive now?
Might be what Blu said ^^ but i would be reflashing and making sure you spoofed your key to the new fw first.