Thought originally that the battery or power supply were faulty. After replacing both, the original and replacement batteries still would not charge.
While looking for the DC-In Board for replacement, realized the Battery Connector was only $10 more so while I was in the same area, I replaced both. Now the battery charges and my grandkids are happy that they have their computer back.
I have used ifixit guides for repairs on the iBook and a MacBook Pro. The guides are great. Could not ask for clearer instructions. My best advice is to label the screws clearly as you remove them. Using color coded markers so you know which length screw goes where is a help. I used small clean cat food cans to put small parts in and labeled each can with the step number I was on when removing the part(s). Then working backward through the numbers made it easier to reassemble the computer.