Macbook Only works when plugged in?
Little Background. Bought 2013 rMBP. Gave my old 2011 MBP to my Fiance as a gift to replace her old 2008 Black Macbook. She gave me her Black macbook to sell for her. Was working 100% no issues at all beside battery slumping a bit. Had it sitting in one place for about 7-10 days because I did not have the charger for it. When I got the charger It wouldnt charge but it would turn on when plugged in. Left it charging for two days always showing green fully charged light. Turned it on while plugged in again and when I unplug automatically shuts off. I was able to reset it and now just sits in recovery. But useless without being plugged in. Tried a different charger now as well and doesnt help.
What could it be in this scenario? Battery? Power source? Something else?
Help is appreciated!
Macbook 2008, Mac OS X (10.6.5)