I will go without gamepad I guess, also need to do extra steps to avoid gamepad reconnectinng if you plug it when Big Box is already launched.
Open the BigBoxSettings.xml file with Notepad (or Notepad++).
Search (Ctrl+F) for the tag: <EnableGamepad> Change the value between the tags to "false": <EnableGamepad>false</EnableGamepad>
(Optional but recommended): Also find the <EnableAllControllers> tag (if present) and set it to false as well. Save the file, close it, then right-click on it > Properties, and check the Read-only box. Click Apply.
One more step, just in case: InputBindings.xml If Big Box is still resisting after locking the global settings, it's because the application is forcing the controls to read via its dedicated shortcut file. Still in the LaunchBox\Data\ folder, find the InputBindings.xml file. Delete it completely (make sure both LaunchBox and Big Box are closed).
The next time you launch the application, it will generate a blank file which, combined with your read-only locked BigBoxSettings.xml file, should never again scan or "pollute" the HID inputs of your controller when you hot-plug it.