Dead battery on iBook.


I have an iBook SE (firewire). the battery does not recharge, in fact the percentage is 0%. I have 2 additional batteries that I tested. Same thing. The battery icon has the prong icon in it instead of the lightning bolt. The powerport glows amber when the iBook is turned off but glows green when the iBook is turned on.

Does anyone have any suggestions on what to test or troubleshoot before I go out and try to find a new battery? Thanks!