I'm technical Macintosh specialist but I have limitations about hardware problems.
This is a Aluminium G4 12" 1GHz DVI model. I changed the DC-to-DC board because I thought this was the source of the problem (the PowerBook doesn't start - no sound, nothing ! even after PMU reset, testing with other power adapters, etc).
BUT, If I start the computer by pressing the power button, after a few minutes, the heatsink becomes warm (the computer is unmounted for the testings of course) - nothing on the screen, no sound, etc...
What do you think is the cause of the problem ?
Many thanks ans best regards