Hi Carmine!
Could be a lot of things to be honest!
Please check the PS3 drive - motherboard ribbon cable (you can test the cable by doing a continuity test on both ends, if it beeps, it’s OK).
Also check the drive it’s power cable.
This issue is common and it could be the drive it’s mechanism which is broken.
I saw this issue sometimes and replacing the drive for another one does work. Make sure to transfer the old drive it’s PCB to the new drive!
If this didn’t solved it, then it’s most likely something on the motherboard (transistor, or something else)…
Please let us know your findings! Good luck!