Some iBook G3s have the problem of their screens having lines or staying black when booting. The problem is with the graphics chip. To fix this problem we must reflow
the the solder beads in the graphics chip. In this instructable I use a heat gun, but you can also use a blowtorch on low. Below is a picture of a ballgrid array graphics chip like the iBook's.
This is a very risky project so don't do this unless you don't want your iBook any more(except for parts).