"Why my TAM doesn't work with a G3/L2 upgrade card"に関する回答You may need the power macintosh card control panel installed for it to boot properly. In my experience I needed it in order to boot without the card enabled first and then install sonnet software and switch the card back on in the power macintosh card panel. Restart and it worked with the new card. Hope this helps.
"PowerBook Won't Read Hard Drives!"に関する回答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.