I need to backup iCloud on my iPhone 6 but I can't, how can I proceed?

[iMore Question]

I need to backup iCloud on my iPhone 6 but I can't

When I click to turn on my phone the screen is still locked and there is a dialogue box open saying the iCloud needs to be backed up. At the bottom of the box is "ok" but when pressed it does nothing and after a few seconds the screen goes dark. I can't unlock the phone and cannot turn it off either. How can I proceed?

 

[Ledsteplin]

Re: I need to backup iCloud on my iPhone 6 but I can't

Welcome to iMore! Do a hard reset.
Hold the top or side power/sleep button and the home button at the same time until the Apple logo appears, then release.
That should allow you to enter your passcode. Then go to Settings > iCloud > back up.