A screen that stays dark or a camera that is not detected after a build is a disappointing moment, and it is almost always one connection on the board rather than a dead part, so it is usually a short fix at the desk you built it on.
If the screen stays dark
Go along every pin of the display header. The solder should cover the pad and come through to the bottom of the pin, with no bridge across to the pad next door and no loose solder left sitting on the board.
A finished joint is a small shiny cone that covers the round pad completely and hugs the pin all the way round. One to redo is dull and blobby, sits on top of the pin like a ball without touching the pad, leaves bare metal showing, or bridges across to its neighbour.
Reflow anything that does not look like that, then power the car up again. In the picture below, the joints marked OK are the ones to copy.
If the camera is not detected
Switch the car off first, then compare the camera module against the camera step in your build guide at circuitmess.com/blogs/resources. It should be fitted the way the photographs show and sit square rather than at an angle.
Check the joints around the camera header in the same way as the display ones, then switch the car back on.
If none of that changes anything, email us at [email protected] with your order number and a clear, well-lit photo of both sides of the board, and we will tell you what we can see.