These battery lights can't tell us anything useful for batteries past a few years. The failure modes would require a mainframe and maybe a Star Trek M5 talking computer. Let's keep it simple. Old batteries fail in a few ways. Dead = easy to tell what's up. Zombie units that rise up on charging but give short use eat up our time trying to coax them back to life. And shorted cells burn up our chargers.

Since it is 10 years old I would hit amazon.com and buy a replacement. Yes I heard your question about the battery being 10 years old but that's a question for the seller.

Hope this helps.
Bob