Key during POST to access One Time Boot Menu
causes No Video issue on Dell Optiplex 360 connected to a Flat Panel Monitor.
This issue is majorly seen in Optiplex 360 Desktops with LCD flat panel monitors.
This issue occurs due to the screen resolution conflicts of the flat panel monitors with the Bios of optiplex 360 Desktops.
To resolve the issue reset the monitor to factory defaults.
Refer to your monitors documentation on how to reset the monitor to Factory Defaults.