Not much to elaborate or for a photo to show. The screen adjuster is jammed. Simple as that - lever lifts, mechanism locked solid…
Had a similar issue with my DVT once. Have you got an Evotech iPhone mount fitted ? Mine interfered with the mechanism as the iPhone mount was tightened too much ! A few carefully chosen washers to space it off the lever sorted the issue.
Looking at the parts fiche, it doesn’t look an overly complicated mechanism and every part is available separately.