d. There is nothing on the monitor display when the NVR is powered on.

Answer:

1. Check the various power supplies.
2. Check all cable connections (HDMI,VGA) to make sure that they are firmly seated.
3. Check the monitor to ensure that it works when connected to other devices.
4. Connect the monitor to the other video display output port (VGA or HDMI) to see if one of the ports has been damaged.