How Can I Fix My Nokia 3110?

Hi I Recently Got A Nokia 3110 From A Car Boot Sale.
I Brought It Home And It Was Working, Charging But Was Locked To Virgin So I Searched Google And Found A Unlocking Code, I Put It In And It Said "SIM Registration Off" Then I Took Out The Charger From The Phone And It Still Said Charging So I Took Out The Battery, I Put In My O2 SIM Card And Put The Charger Back In. And Now All I See When I Plug In My Charger Is A Little Battery Icon In The Bottom Right Corner of The Screen And The Screen Seems To Go On And Off/The Icon Goes On and Off. And If I Push The Charger Into it A Bit More The Screen Just Flickers On/and Off With No Icon, Does AnyOne Know What I Can Do, Eg. New Battery/New Charger/New Phone? Email Me:
Thanks
Nat