I have the same issue with my 3400c. When I got it used it was missing the pram bat and had some issues with the power jack which I fixed. Since fixing that port my internal HD and trackpad refuse to work (they did at first). When I start from disk tools no drive is shown, and the trackpad is dead. However when I plug in an apple adb mouse the trackpad reacts to touch but barely. I think I may have heated something I shouldn't have on the logic board. The drive works in other machines and boots just fine. the ribbon cable looks to be in great condition. I'm guessing the logic board is messed up. I have no issue trying to fix the board but I don't know where the IDE components are. it may just be the ribbon connector on the board but its nearly impossible to tell and wouldn't find a part most likely anyway, this would explain why both trackpad and HD are having issues. They both power on at boot... but nothing happens.