Are all steps have een described followed with store manager on site and is it confirmed it did not help? Please confirm.
"In the back of the KC3 (Silver box) there is a switch for DVI/VGA. Probably the switch is set to the incorrect position. Ask the manager to change the position of the switch then Power off and back on the KC3 box. Please make sure the cable is secure on KC3 and Monitor"
If so please follow up with a proper Hardware dispatch email same as on POS stating HW is broken and needs to be replaced