Hard-Reset iPhone with broken Power-Button, when it stucks on staus bar

Hi,

Yesterday, I've updated my iPhone 4 to iOS 7.1.2 (i think). I haven't installed any Jailbrakes, or something. Unfortunately my iPhone stucks at the status bar, since 8 hours. The attempt, to make a hard reset fails, because the home button is broken. So I tried to reset it with iTunes, unhappily iTunes wants a permission from my iPhone to connect.

Is there another way to restore or to reset my iPhone? A friend told me, to wait, until the battery is empty. Is this a good solution?

Thanks, in advanced.