Why won't my Macbook battery charge?

I bought a battery on ebay a few months back when I thought I was buying a macbook from another guy with a bad battery macbook. It has sat out for a few months but it only shows having 3 cycles in the "about this mac" page. It was new as of a few months ago, then sat around my desk until trying it on this other macbook.
This macbook that I am currently trying to get working did have a battery with 325 cycles on it. It was not charging according to "about this mac."
When I put the new battery in, the battery icon at the top of the screen has an "X" in the middle.
I just reset the SMC (or I followed the directions on how to do it, I have no idea if it worked or not cause there is no mention of a chime or ding or anything to let you know it was successful).
Any other thoughts?