Actually, there is a ridiculous amount of information about what happened to the Bionicle characters, spread across a bunch of books, comic books, online story serials, and various forms of media. It was so bad that they had to get the author on a discussion forum to explain what was canon and what was not. I wasted so many hours of my life discussing that. Why?
I'd throw you a bunch of links to get you started, but here's the thing: DO NOT join the Bionicle discussion forum. It's a very bad place for Christians. You do not want to hang out there. When I first joined, it was okay and kinda made sense, and I was spiritually naive, but that place is BAD now. I'd write a long post explaining why the place is bad, but the bottom line is this: they ban you from talking about the Gospel or Christianity...and then there is some other really bad stuff...and yeah.