When reassembling, ensure that the press connector and the ribbon cable are hanging outside of the chassis so that you can reattach them. The ribbon cable in particular is easy to leave inside of the case where it may get bent and crushed as you reassemble it.
If your circuit board is not connected via a ribbon cable, then you probably want to stop here and follow the standard Xbox One X hard drive replacement guide instead. My Project Scorpio machine is physically identical to a standard Xbox One X. I followed that guide, which has subtle differences to this one, and it perfectly describes my machine.