hi,
had the same problem with the stuck power button. as user 'louiszro' suggested follow the instructions to dis-assemble your ipod just like for exchanging the headphone jack, but stop at point 13.
after that, remove the 3 buttons('plus', 'minus', power - connected to each other) by removing the 4 screws. the problem with my ipd was that the very small black plasic peace
(shown exactly here: http://tinypic.com/view.php?pic=14t62x4&s=6)
wasn't were it is supposed to be - just compare with the other two buttons. i used a little bit of '2 components glue'(don't know the exact english term for that...) to stick this plastic peace onto the middle - backside of the power button.
when assembling: be sure to push the 2 connectors from the LCD so they have proper connection. at first my player stayed black - thinking i fu**** it up - but the connectors just weren't sitting properly... check that out before assembling further.
good luck - work carefully, and nothing should break! of course - if you have warranty, try exchanging the player first...