DVLED Display with an entire column of unlit LED Modules. 

Answer: There may be poor connection or loose wiring with the connectors from the System Control Box to the LED Module adapter board.

Solution

The column's most bottom LED Module will need to be removed with the Vacuum Suction Tool in order to access the connectors.

Check for loose wiring (Power cord or Ethernet cable) and connect as needed. Reinstall the LED Module to complete troubleshooting.

Related links

"Why is an LED Module showing a colored straight line on my DVLED Display?"
"Why is a single LED Module not on even though my DVLED Display is powered-on?"