sounds like a loose chip to me...
you might try a quick test.
put the iBook on a hard surface (desk) and push as hard as you can with your left hand using one or two fingers just to the left of the trackpad (just below the split of the apple key and and the space bar), and then with your right hand hit the power button. if that doesn't work and you have nothing to loose, try a clamp to apply more pressure, but only if you really don't need this to work ever again. think: half turn - try - half turn - try - etc. i've seen lots like this with the same symptoms.
if this is the 'loose chip' failure, you might get it to boot. if it does boot, and then you remove your left hand (or pressure)it will likely freeze. best of luck.