Introduction
How to exit the mapping UI, when the UI has no option to exit via the touch screen using a USB keyboard.
Procedure
Connect the USB keyboard to your device.
For the NavVis VLX use the external USB-A port beside the handlebar. Refer here for location.
For the NavVis MLX you need a USB-C hub if your keyboard only has a USB-A connector. Refer here for location

Exit Application
Use one the following to exit the device UI:
By pressing Ctrl+Q
By pressing “Windows“ key and press “X“ to close application
By pressing “Alt“ key, and click “File → Quit“ from the top left menu bar:

To fix the underlying issue on your device contact NavVis Support for a remote session.
Refer here for information on how to open a remote session: How to Set Up NavVis Remote Support from Ubuntu , and send the remote connection ID/password to support@navvis.com