This is caused by resolution compatibility issue. 

The default output resolution of the DVR is 1024*768, which may not be compatible with some

screens.

Here is how to solve it:

1. Connect the DVR to any other screen via VGA cable; (or you may also try any other screen via

    HDMI to see if you can enter the menu) 

2. When you are able to see the menu, click right button on mouse, go to Main Menu – Setup –

    Basic – Video Output; change it to 1024*768 or any higher resolution that your screen can

    support; apply to save it. 

3. Connect it back your primary screen via HDMI. You should have it worked with the screen.

If this can't help you, please feel free to contact us.