i just got this iphone 3gs from a guy who has told me its jailbroken and running 4.2.1

when phone is turned on all is showing is the itunes logo and usb lead below picture.

im trying to restore to 4.3.1 but im getting an error
an unknown error has occurred 3140

any help is appreciated all i want is the phone working im not bothered about a jailbreak or unlock.thanks in advance