Screen flashing and unresponsive

I jailbroke my iPhone today and was using the app Activator, trying to set my phone up so that I could unlock it without needing a passcode (e.g. by swiping the clock left). When I confirmed the new settings (using TapTapPass within Activator) the phone suddenly went black and then started flashing between screens: the home screen, lock screen, and other apps such as Twitter. It has been rapidly flashing between these screens for about an hour.

I can't do a hard reset because the lock (sleep/wake) button is broken on the phone.

I'm not sure if the cause is the jailbreak, Activator or some other problem.

Is there any solution? Thank-you in advance.