Here is the text of the fix copied
in full - for the benefit of users with the unfortune to be hit with this bug - A big thank you to the kind smart Japanese folks who found the workaround!!
Related information
https://discussions.apple.com/thread/3787251?answerId=17786746022#17786746022
Recovery method using Emergency call
I could recover my iPhone 4S by using the following method. The condition is that your device is using “Passcord Lock”. If you did not set up it and your device was enabling “Find iPhone” function in the iCloud, you still have the opportunity for recovery. Please access to https://www.icloud.com/#find and try ”Remote Lock” to your device. By this operation, your device will be “Passcode Lock”.
When you unlock the slide, “Passcord Lock” will be displayed on your device.
Tap ”Emergency call”.
Tap ”left arrow” button.
Repeat No.2 and 3 at several times (About 10 or 20 times). If ”Siri” setting is displayed, I think that the trouble will be resolved.
* If the operation could not succeed , you will loop it and try No.1 again.
I selected “disable Siri”. And then, tap “Start iPhone”.
If ”Home” is displayed, I strongly recommend to back up your device in iTunes.
* You connect your device to your PC and select “Backup” from context menu (right click in the device name of iTunes)
Finally, please enable “Siri”, disable “Limitation” in General, and disable “Passcord Lock”.
* At least, you had better use the above settings until the trouble is fixed.
Recovery method 2 using Emergency call
When you unlock the slide, “Passcord Lock” will be displayed on your device.
Tap “Emergency call”.
Pushing “Power” button for several seconds.
When “Power Off” slide is displayed, you try to cancel for back to “Passcord Input”.
Input “Passcord”.
Recovery method using Facetime
In case of using Facetime in your device, the following method is effective.
Call from other device to the trouble device using Facetime.
Move to Home in Facetime.
Disable “Passcode” and “Restrictions”.
Recovery method (Final countermeasure)
Back up your device using iTunes.
* You can back up it during the trouble.
Reset device with recovery mode.
Set “Passcord” in General setting.
Restore from Backup data.
Tap “Emergency call” button in “Input Passcord”.
Pushing “Power” button for several seconds.
When “Power Off” slide is displayed, you try to cancel for back to “Passcord Input”.
Try to repeat from No.4 to No.7.
If “Siri” setting is displayed, please go ahead the setting process.
If “Home” is displayed, please disable “Passcode” and “Restrictions“.
