Their mom tripped over the power cable, the tip broke off inside the DC-In plug-in, and there was little hope left for the old G4... so I gave it one last college try to diagnose & if reasonably inexpensive, attempt to repair & reboot.
Turns out the diagnosis was easier than expected, once I found certain similar stories on your site... so I ordered the DC-In Board, which was easy as pie on your site, and in less than a week the part was waiting for me in the mailbox. Part of the diagnosis was following your excellent step-by-step process, complete with vivid pictures, on disassembling the old G4 laptop. I was originally afraid of breaking the old, partially cracked, outer case, but the instructions clearly showed where to locate certain tabs and how to properly remove the back plate. In only a few minutes I was able to get right to the DC-In board and remove it, only to find what I had expected: that there were pieces of the plug still broken inside, and that the plug clearly was not reaching its objective contacts. Hence, diagnosis complete, part order verified! Once the part arrived, and I got back to the laptop after a week, it was equally easy to replace the part and work in reverse order putting everything back together for a completely repackaged G4 iBook... Mac Happy Chimes away...!
Not even laptops are too difficult, with the help of iFixit... thanks for all your help!