Updating imac firmware
Do not shut off the power on your i Mac during this update.
Loss of power could result in your i Mac failing to start up.
Restore your device to factory settings and then set your i Phone up as new.
Again, you lose all your data this way but it’s Apple’s latest advice on how to resolve the ‘Slide to Upgrade’ bug.
If after following the above, your i Phone is still stuck on the upgrade screen, try restoring your device in i Tunes.
If you don’t see your device in i Tunes, you need to hard-reboot your i Phone to stop it from freezing.
However, before the first step, try logging in to i and removing your device from the Find my i Phone portal.
In some circumstances, your frozen i Phone will be able to detect the protection has been removed and allow you to continue as normal.
Without proper updates, those EFI systems could be vulnerable to sophisticated attacks that are hard to detect and cannot be resolved simply by updating operating system software or even replacing the hard drive.
The vulnerabilities they identified, though, most likely apply to other vendors as well, they said.
"Our research has shown there are considerable discrepancies in how Apple provides security support to its EFI firmware as compared to how they support the security of the OS and software," Smith and Bruienne said.
If this does not help, call Apple Care or visit an Apple Store.
Although backing up and immediately restoring to that same ‘buggy’ backup seems redundant, it actually flushes out the weirdness and when the phone boots again it will be able to complete the upgrade. Update: Apple has now provided additional recovery steps.
Search for updating imac firmware:
To do this, press and hold both the Sleep/Wake and Home Button together for 10 seconds or more.