A screen that stays dark after a build is worrying, and in almost every case it is one of the display solder joints that has not quite taken rather than a faulty board. That is a five-minute fix.
Go along the display pins and check three things on each one:
The solder has flowed right around the pin and covers the underside of the pin and its pad, rather than sitting on top as a ball.
No two neighbouring pins are joined by a bridge of solder.
No loose blobs or offcuts of solder are left lying on the board.
The image below shows joints marked OK next to ones that need reworking. Comparing yours against it is quicker than testing anything. Reheat any joint that does not match, add a little fresh solder, then power the device up again.
If the screen is still dark, message us here, or email [email protected], with your order number and a close photo of the display pins. If the part turns out to be defective we replace it free of charge, and we will tell you either way.