so i'm shipping back to apple my ipad 2 and run into a problem while trying to restore it. its jailbroken and it stuck on a screen with a usb cable and itunes icon. and when i try to restore it it gives me an error 21. so i tried another computer (windows, both dont have antivirus soft) same error and on top of that i cant get out of the restore screen i tried to press power and home button as per instructions etc. but it seems the device stuck on continuos loop with the restore screen. also i tried to delete and redownload the restore os file but no avail. any help would be greatly appreciated i need to ship it back on monday. thank you!