My Problem
My MacBook Pro battery would only work if the charger was plugged in. I had spilled water on my keyboard and had to replace that, so I don't know if the water damage got to my battery too, or if it was because I didn't charge the battery for a while.
My Fix
All I had to do was replace the battery.
My Advice
Remember to charge your battery often!
Written on December 10, 2011