Answer:

Cause 1. The video output resolution of the NVR is not supported by the TV/Monitor. 

Solution: Ensure the lowest resolution of the TV/monitor is no less than 1080p, or it won't be able to display any video from the NVR. Try to log into the NVR on LAN and change the output resolution of the NVR and try again. You can change the NVR output resolution via the menu of the NVR. 

Cause 2. HDMI/VGA cable is defective.

Solution: Check whether the cable is defective by using it to connect other devices to the TV/monitor and see if it works. If it doesn't, please use another HDMI/VGA cable that is shorter than 15 m and try again. 

Cause 3. NVR cannot be powered on. 

Solution: Ensure the power adapter of your NVR is working. If not, please use another one to power the NVR. Check whether the LED on the adapter is on (only for Sansco PoE NVR). Check the LEDs status on the front panel of the NVR.