So my sister gave me her old iphone 3gs when she upgraded to the iphone 4. I was very excited yada yada yada but my sister forgot what her passcode was to her phone since she hasn't used it in months. I put the phone into DFU mode to recover it on my computer but I keep getting error 1015. I'm not trying to jailbreak it, all I want is just to go back to the factory settings like a normal restore would do for you but I can't get around this damn error. What do I do?