here is something you can try, i repair and sell ps3s and over time i have replaced lasers and still the same thing, with out going to technical.. first do a data base rebuild, some times a ps3 loses its ability to play anything. when doing my repairs, i have had the cover off the bluray and i have a clear disc.
i inserted this disc with the magnetic holder off the drive to see if the the laser was glowing, it was on both bluray (blue light) and dvd(red light), the icon would spin up but nothing showing in xmb, i then went into hidden menu and done data base rebuild and behold it then started reading and playing,. i always do this first now before i even look at replacing the laser, this will not work if laser is faulty.. that is why i use the clear disc at first. give it a try, it may work for you.