I had the same problem with the FP of a friend of mine. The solution was to install the Xposed Framework and Gravity Box and enable Allow all rotations (and Navigation Bar), to switch the lower non-working part of the phone to the upper part.
After having tried everything with ADB etc… the most trivial idea struck me! Here it comes:
- Download the Xposed Framework and Gravity Box to another phone.
- Activate Bluetooth on the broken FP (do so through the notification bar). If you are having troubles with pairing, try to access the settings.
- Send the Xposed-apk with the other phone to your FP. The file will appear at the top of the screen, so no need to use the lower part. If having troubles during installation, use the landscape mode. (Before installing the Gravity Box module, a restart is required. Edit: Be sure to disable any PINs / screen locks before that!)
- After the restart do the same with the Gravity Box module.
- To access the Xposed Framework, once again go to Settings > Xposed Framework > Launch.
- In the Gravity Box module, check Allow all rotations (and Navigation Bar).
Does this work for you?
This kind of is my first tutorial, so please tell me, if I can improve understanding.