Ok, so it appears my battery is worn out, and that it is unable to hold a charge properly anymore. So, I bought a new battery. That one didn't work, it fit physically, appeared to hold a full charge, and then once it discharged it was unable to charge back up again. I got a couple replacements too, neither of these worked. These batteries were off eBay, from someone with pretty high feedback. Anyways, I was wondering why these batteries aren't working, and since they aren't, what you recommend I do to fix this problem.
That's the danger with buying PC parts off of ebay. Chances are that the batteries are shot. I'd file a PayPal complaint to get your money back and send the batteries back to the seller. If you need a new battery, buy a brand new one from a reputable source.