Restoring problems

So im trying to sell my iphone 3gs to a friend and i need the money for it. i was running on iOS 5.0.1 and had it jailbroken with nothing else on it. and yesterday it was having problems and it kept rebooting constantly. i restored it without realizing that the new iOS 5.1 came out and id have to update it to that. it was too late before i realized it though. now it still has problems with the startup setting up the phone as a new iphone. it wouldnt let get past wifi because it was disabled..? it was working fine the day before. and so i tried restoring the iphone multiple times AGAIN and instead it gave me an error at the end of the restoration process. it said iPhone could not be restored error (-1). i kept looking up error -1 but never found anything. all i found was error 1 and didnt want to believe it was the same. so now im stuck on trying to restore on multiple different computers. and yes, i have put it in DFU mode to restore it. Please help!!