V4 Problem

[KRONIK]

I was trying to mod my ps2 I took it apart but reliazed it was a v4 motherboard so I put everything back togeather and when I tried to play a game it came to the browser screen and said can't read disk I haven't tried a music cd yet but I have tried turning it on and off again could it be possible that some dust got on the laser and I need to just clean the laser or is it porbally a dead lazer thanx for any help