Seriously dude. The 1st thing you have to dop on these situations is undo all modifications. Remove modchips, fixes, jumpers, anything.
Try to have the PS2 to it's original factory state. Then you go try to fix what is wrong. Sometimes a modchip goes dud and make you think the laser is blown.
Good luck with this problem.
Since that PS2 had fixes applied to the input of the RS2004 chip I would check carefully for broken (physically broken) resistors at the fix region.
SCPH-10000_GH-001 SCPH-15000_GH-003 SCPH-18000_GH-008 SCPH-30001_GH-005 SCPH-30000_GH-016(V4) SCPH-30001_GH-010(V4)
2xSCPH-10190, 2xSCPH-10350, 2xSCPH-10280
"**** j0 hackers!"
-Sjeep (As seen on TOXIC OS ELF...)