We have an old Apple iBook g4 that my 10 years old son uses for his school work. He's rough with it and it's been dropped so many times. It was working fine until the power cord broke. We replaced the power cord and was working fine for a week before it no longer turned on. When we took it to a repair shop, we learned that the power cord works, but were told that it's not worth fixing the laptop.
I followed the on-line instruction and replaced the DC-In board. The instructions and visuals were easy to follow. I cannot believe I did it!! The iBook works just fine!!
What helped me was taping the tiny screws down next to the holes it came out of. If there is no space, tape it to a piece of paper and label where it goes.