As in, the display module from a piece of gear? Usually those expect VSYNC and HSYNC signals, but they should have free-running oscillators inside which start up normally, even if not drawing a proper raster. Which certainly explains the high voltage and all that (yes, some crackling static sound is typical of high voltage starting up), but diffuse flashes (often with a sparking sound, louder than static) probably means something bad like internal arcing.
Has it seen bad conditions, moisture...??
Tim