screen flickers, then system crashes
For the past day my laptop has been crashing. It will run for about 5-30 mins just fine. All of a sudden, the screen will fail (it will sort of "swipe cut" with a rainbow trailing edge). With a few attempts, i can get it to come back on, but only after turning my laptop off, then back on (sometimes it does nothing but run the fan for awhile without turning back on)
Actually, your iBook might be suffering from a failing GPU chip/connection
There's a documented issue for the iBook G4 who has the fellowing symptoms at boot up: no chime, screen stays black, fan runs full speed, no other activity.
This problem is often related to a IC power regulator named U28 and located near the DC in board cable socket under the iBook G4 logic board. The IC power regulator has 40 pins but only the pins 1 and 21 can be desoldered from the logic board and causing a power issue at boot up. Just briefly applying a fine tip from an iron solder gun to the two pins to resolder them can restore the IC communication with the logic board. A Google search would give you more info about the U28 issue.