Probeer uw iphone eens in DFU mode te zetten en de laatste versie er opnieuw op te zetten:
* Connect the iPhone to your computer, with iTunes running.
* With the iPhone still connected, hold down the POWER and HOME buttons until the iPhone restarts (screen goes black)
* As soon as the screen goes black, immediately release the POWER button, but keep holding the HOME button until the iPhone appears in iTunes in recovery mode (if you're using Windows, you may also see Windows report a "New USB Device Detected" message).
* Once the iPhone appears in iTunes, use the "Restore" button to restore the firmware back to the original setings.