Take the side off and check the cables are all connected ok, one might have come loose in transit, make sure to earth yourself first for static(by touching the metal part of a radiator)and the computer is disconnected from the mains.
OnePlus 5 review
Best of the Grad Shows 2017: UAL Central Saint Martins
MacBook Pro 15-inch (2017) review
Comment connecter un MacBook à une TV ?