I bought a used ipad and it came up jailbroken. i don't want/need that so i just erase data and contents from the settings menu. for the past 3 hours the ipad has the apple logo loading. shutting down sometimes and then coming back to the same scree. i try to reboot it pressing the 2 buttons for 10 sec. it go back to the same mode... then i plugged it to my MBP and run itunes. the ipad does not appear on it... any suggestion??