Filmborn shuts down every time I try to open it, and or I see a black screen when the app opens.
The best course of action when this happens is to first, delete Filmborn, then perform a forced-restart (hard reboot). On an iPhone 7 plus or earlier model, do this by simultaneously holding down the home button and power button on the right side of your phone. Continue to press these buttons until the screen goes black. Release the buttons and wait for the phone to restart.
If you have an iPhone 8, 8 Plus or X, you can force-restart your phone by pressing the Volume Up button, then the Volume Down button, and then press and hold down the Power / Lock button on the right side of the phone. Continue to hold this button down until the Apple logo appears on the screen. Release the button and wait for your phone to restart.
Once your phone has restarted, go to the Filmborn page in the App Store and download a fresh copy. Always install Filmborn while connected to a stable wifi signal. This will ensure there is no disruption during download!