HELp!

ok this is problem ,mine PSP 2000 was working fine but last time i disconnected from pc it would not not turn on. if i remove battery but adapter plugged in, psp starts fine wid green light . But not turning on with battery. if i try to charge battery, the battery indicator come n goes . battery information is Blank except power source external is displayed,orange indicator glow and psp turnoff after about 2 minutes.

I go to system settings < battery information it just says

Charge Level -
Hours Left -
Power Source - External
Battery Status -

I unplug the Ac adapter. my PSP shuts off.

ANY IDEAS ??