howdy! one of the ender 3’s in the lab has suddenly gotten a blank screen issue.

the display unit is blank.

I have swapped display units with another ender 3 v2

I have swapped display cables with another ender 3 v2

I refreshed official creality3d factory firmware on both mainboard, and display unit. display unit was black, then blue, then orange (I think it was orange, might be a little color blind. looked red to me, but others said it was orange.) 

no dice. display unit still only displays black, the screen is backlit but blank.

any help would be appreciated.