faulty,,, iphone 3gs,, signal problems .

iphone 3gs, comes with box charger and usb unlocked to all networks - jailbroke was working fine on the 02 network, then i let my mate jailbreak the phone and now it gets 1 bar ov signal and wont ring out... this phon does have light scratches on the front wich ar not visible when the light is on and the back cover also as signs ov wear and tear....... i am selling this phone for 60 NO OFFERS PLEASE DO NOT TEXT ME A OFFER..UNLESS ITS A SWAP FOR ANOTHER PHONE.. I WILL NOT TAKE NO LESS.. 07831301781