I have been trying to revive a Pismo PowerBook G3 400 Mhz for secondary uses. When received, the Pismo had only 64MB in its bottom RAM slot, and no RAM in the top slot. It would only boot with the alternating folder icon/question mark, but it would boot. I sought out and obtained an Airport Card, and two Pismo RAM sticks, 256MB and 512MB. A few days ago I obtained the Pismo 256MB RAM chip, and put it in the top slot on this Pismo with the original 64MB on the bottom. The Pismo ran okay with the 256MB + 64MB, except I had to boot from an external firewire drive, running Tiger 10.4.2. I figure the old 10GB internal can't handle the Tiger system I put on it (or Panther, which I also tried), or more likely it's just had it's day. Then yesterday, the 512MB chip arrived, and I've installed it. I was going to replace the hard drive but couldn't (I don't have the right Torx screwdriver yet for the hard drive black screws) so I put the computer back together, 512MB chip on the bottom and 256MB on top. It stopped working *totally.* Black screen, so startup sound, no sounds at all, nothing spinning, nothing at all. A reseat of the processor card brought a little noise, but nothing starting up, no chime, no display. I tried the reset button, retraced all my steps taking it apart and back together 10 times, reseated the RAM carefully in different combinations, put back the original 64MB chip on the bottom and the 256MB on top, and other combinations. Now nothing works. Nada. Zip. No combination of the RAM works either, nor any of the RAM by itself. Any idea what I've done to this poor machine? Everything looks fine, and it sure was working, although without the internal hard drive, only an external firewire drive, before I tried adding the additional RAM yesterday. What have I done? I used the pbfixit.com instructions for changing RAM in a Pismo, so I went through these steps: Computer off, unplugged, grounded, removed the battery, removed the keyboard, removed the heat shield, removed the airport card, removed the PRAM battery, removed the heat sink, removed the processor card that has the RAM slots on it, replaced or switched the RAM, had a look at the hard drive, replaced it carefully without having disconnected it, and then all of that in reverse. I have removed the PRAM battery again. I have checked the mmc2 slot for bent pins. I have made sure I heard the 'click' when reseating the processor board. I have reset the machine with the power management button on the back. The power on button did not power anything at first. I hear a very small noise now when the power is pressed, but there is nothing on the display, and there is no startup chime. Thanks for any advice you might have, I hope I'm just missing something easy. And no, a search online provided only what I followed above.