Why there is no video shown on display?

In this case, the ouput video resolution of DVR exceeds the maximum resolution supported by display:

1, you can change another display with higher resolution.

2, Login the web interface of DVR, select a lower resolution output in system configuration.

3, Login the web interface of DVR, restore the DVR to factory setting.

(suggestion: Adjust the ouput resolution of DVR according to the display)