Hi @sspiller
This LED, D6, is an indicator that all power supplies for the board are ON (and GOOD) and the image sensor is OUT OF Reset.
e5f4c9b6-8d8a-4346-a0ce-833bf912f621-image.png
When you see it toggling OFF, it implies the VOXL/VOXL 2 is holding the image sensor in reset.