Did you try to boot your PS2, when the MI is turned of?
Did you try, if the connections for V/A on the backside of PS2 have (full) contact?
Did you try to reflash your MI in Flash-Mode.
Did you try to boot your PS2 with turned on MI, but with standart-Configuration?
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