Iphone update
iPhone 6, tried to update, error 56, now stuck with screen showing plugin to iTunes. Can't do anything else.
iPhone 6
Then you have to plug into iTunes. See: If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled - Apple Support
As to what happened, see: Get help with iOS update and restore errors - Apple Support
Error 56 is frequently (but not always) the result of a botched repair. Restoring with iTunes will sometimes fix it.