Thanks CaptureYourAction, it would appear to be a problem with the ribbon cable or connections.
swivelling the camera lens will cause a working start to freeze, and occasionally a frozen start to work.
Unfortunately when I looked on amazon UK it say my time for return has passed, despite the order being in May, and I can't find a way to contact them.
The seller was Boblov and the item was stocked by Amazon so no idea how to go about a return
This leaves me with the choice of buy the same again (and TBH the failure does not instil confidence in the brand) or find a suitable replacement.
I found a Toguard CE20 and an Anker ROAV that seem OK but I cant find much about the makes on these forums.
Or spend a chunk more cash on a 2017 Street Guardian SG9665gcV3 or Roadhawk Vision.