The fix for issue MDL-72029 in Moodle 4.0.2 prevents proper operation of MoodleBox. This bug should be fixed by the resolution of issue MDL-75375.
Meanwhile, do not update your MoodleBox to Moodle 4.0.2. Stick with Moodle 4.0 or 4.0.1+.
I'll update this notice when issue MDL-75375 is fixed. Don't forget to vote and lobby for its quick resolution.
Updated: The bug was quickly fixed by MoodleHQ. It's now safe to upgrade your Moodle instance on your MoodleBox.