Sometimes, when installing a new update from the App Store, something in Apple's updating process goes wrong and reboots the device. When the device reboots, it can go through a cleanup process which can take a while to run. The longest we've seen it take is 30 mins or so. Unfortunately, the whole installing/rebooting process is all in Apple's iOS, and is out of Instagram's control.

If you've waited for the device to reboot but it's still not working, you may want to:

• Wait until it runs out of battery and try booting
• Try different combinations of plugging the phone in / restarting the computer with the phone plugged in / unplugging and re-plugging the phone

If these troubleshooting steps do not help, please contact Apple support.