Maybe your ps2-laser is focused to writable media.
-Try to insert a disc/an original and don´t start it.
-Go to the main-menu-screen of the PS2.
[Thought, you reach the option, by pressing TRIANGLE.]
-There was an option "diagnosis" (or something...). Turn it on and let it read your disc sometimes.
Try to start your disc.
It might need several retries, a poweroff/reboot/reset but it might work in the end.
PS2 V7/DMS3 V2 (FW:2.4b7); Seagate Baracuda 200GB
PS2 V7/CC1.0 (FW:34 hacked v2 BM:2.1.6); Maxtor DiamondMAX9 PLUS 160GB
PS2 SCPH-30004R; NoMod+NoLaser
3xSony MC 8MB
MAX/Datel 16MB with Boot-CD
Custom FMCB 1.8b+ Beta-Build, my AIO 0.5, Sony&xRhino-Linux