My Concord DVR is not displaying anything on my laptop screen

Laptops can not be used as display screens via their HDMI or VGA ports - those are outputs, not inputs.

The HDMI or VGA outputs on the Concord Security systems are intended to be connected to screens such as TVs and computer monitors, so connect your system to a nearby TV to set it up, if you have one.

Otherwise, to view and record on a PC, buy a HDMI USB capture dongle such as XC4661, plug the Concord's HDMI cable to the dongle, and connect it to your PC's USB port. 

You can use the Windows Camera app, or OBS (Open Broadcaster) to view and record the Concord's video output.