Monitor black, light flashes

Monitor won't power up or down. Green on/off light flashes, but won't turn off or turn on. Screen is black. Seems like monitor screen flashes a bit at the same time the green light flashes.

Tried unplugging the unit and when plug back in the same thing happens - flashing green light and nothing on the screen.

Computer did have an error code on when shutting down and froze. Had to hard shut down the PC. When first brought PC up, the monitor indicator light was on (green), then started flashing when I tried shutting it down and rebooting.