My iPhone 5 was dead again. (Yes, yes, I still use iPhone 5. I plan to do the upgrade before the end of the year.) The phone went dark and cannot be booted up. It showed the Apple logo for a while and went dark again. The trick of pressing home button and power button together did not work. I had to do the hard restore at the end. Restore iOS Make sure the latest iTune is installed on the Mac. Connect iPhone to the Mac using the cable that came with your device. (This is important. Third-party cable may not work.) The message: "There's a problem with the [your device name] that requires it to be updated or restored." will be displayed on the Mac. Click Update to reset the phone. I was able to get the phone back in 20 minutes. Do not click on the Restore button, which will set the phone back to the factory default.