My son dropped and cracked his iPhone 5c screen. You can't make out anything on the screen, although it still powers on and you can see the very top left corner still. He got a new iPhone for xmas, now just want to sell old one for parts. I restored it using iTunes but can't verify that all data was wiped clean. I deactivated it from both AT&T and my apple ID. Can I be sure that there is no personal info on it anymore? Thanks.