Honestly the best way to fix it is if you go to a computer repair shop. I wouldn't reccomend trying to buy the part and replace it yourself. It's a pain in the butt. Will take hours and probably not gonna keep your warranty. Is it still covered? If it is covered under a 1 year manufacturers warranty you can get it fixed. That's the easiest way to do it.
To: victor001200, Your battery is shot. You probably charged it poorly so now its not working properly. Buy a replacement. Their like $30 on ebay.