Oh boy, I think I just killed my iMac while upgrading my internal HD to 160 GB and super drive to a dual layer burner for my iMac G4 800 mhz. Initially everything was going well. First I used carbon copy to back up my original HD to an external HD, then took apart my iMac and placed the external as my internal. Put everything back together and pressed the power button, everything booted up fine. OK, now for my dual layer dvd burner. Disassembled my iMac as I did before and took out the existing Pioneer burner and replaced it with a NEC dual layer burner. Put everything back, turned on the computer downloaded and installed patchburn so that my new optical drive would be recognized. So far so good, everything is working just fine but then noticed that I missed a few screws. Damn, tore it apart again, looked around and found a home for each missing screw. Bandaged it up again and when I press the power button nothing happens. OH CRAP! Ripped it apart once again, made sure all connectors are tightly secured, all screws in place, and made sure there were no damages to wires. Nothing wrong that I could see, put it back together, pressed the power button and still nothing!!! Not even a screen blip, no BONGGG, can't hear the HD, just plain silence. What went wrong?? I spent about two hours trying to trouble shoot and right about now I'm at a loss. HELP!!!