OK, I remember seeing this topic a few times but can't track it down when I need it.
I have a V4 in front of me that when a disc is placed in the drive it spins up very fast but does not read it, it goes to the browser screen, meanwhile the disc is spinning at full speed (If eject is pressed then it will pop out the disc still spinning on the tray).
This is a non-modded console, I have swapped lasers, adjusted pots and still the same thing. I was thinking it might need a chip replacement (BA6664FM) but I am looking for a second opinion before I start doing work which I might not need to do.