If the Bluray player in the PlayStation 3 fails, it could be a bad laser. This video show "how to" trouble shoot the Bluray player to determine if the problem is a failed laser or something else. If there is a bad laser, how to replace it. It also explains when and why you have to "remarry" the Bluray player.
If you need instructions on PS3 disassembly, this video is very detailed:    • Sony PlayStation 3 Fat Disassembly