the ps2 powered down when you held eject? wierd???
I'm takin you did the install recently so open it up and make sure that all the ribbon cables are still in the mod. and the mod is pushed in as far as it will go.
If you're still not getting anywhere check the ribbon from the power and eject buttons, it's easy to trap whilst, or when pulling the ps2 apart. If you've ripped that, then check on the net for replacement.
i saw
www.lik-sang.com selling them. Let me know how you get on.