Ok so here it is...
My 'mate' kicked my laptop over and broke the hinge on it. I bought one off ebay to use for parts, swapped out the hinge, had approx 18 screws left over afterwards, then when I turned it on it turned off again...Did the normal resetting of various things, but once I got it back on again just bevfore it turned off it asked me if I wanted my machine to restart, sleep, cancel or shutdown. This made me believe that the power button was sticking down, something I later realised was true as when I shook the machine (lightly) it turned on with the long single beep, flashing power light then startup chime then turned off. SO...I took the back off, and the shield, unscrewed then rescrewed but not so tight as I thought that I overtightened the screws for the upper casing forcing the power button to be in a constant state of depression.
I am currently using it (anad have been for a while now) and it hasn't turned off, only way I could do this however was to take out the 2 long hexagonal screws near the hinge.
Anyone have any ideas what I've done or seeing as it's still going without those screws in is it safe to be in this state?

1.42 Ghz powerbook G4 white iBook running leopard with 1.5gig Ram

Thanks in advance