Same glitch again yesterday evening. This time no media inserted. LED Lightshow as usual during booting, then as the EngineDJ logo + version number refresh a final time and prepare to fade out for the browser, all LEDs die, minus the jog screen background illumination.
Rebooting solved the issue.
Could a mod speak up if the dev team is aware of this problem? Otherwise, I will have to open a ticket. Another user shares similar issues here.