G4 PowerBook partial boot?

My G4 VGA model will chime halfway then stop. Although the caps-lock light stays lit and the battery will charge, there is nothing else showing that it is powered up.

Half chime...that's IT!

I AM "using a Generic OS X build" 10.4.11, and the laptop was booting fine until one day last week, when it booted only half way through the chime. The model number has rubbed off the bottom, but there are only three choices in the ifixit repair guides and this is NOT the DVI model. This is a Titanium 667MHz, so it must be model M8407. I have torn it down and put it back together, and plugged another start-up button into the board; the new start-up button did not change things so that's not the problem, and the reset button is not the problem. Since it is hanging up half way through the start-up chime, the "failing after POST" tells me what's going on: failing before the standard gray-screen, but does not provide a prospective solution. I will try an external monitor, but only if the VGA port can link to another VGA port on another LCD that I know to be good.