Check for any screws under a label.
No labels really, but I have it figured.
You have to remove the upper back feet then the front bezel (three screws underneath, then wriggle off which is tricky without damaging the plastic clips which hold it at the top), which reveals a further 7 screws around the front of the top cover - two on each side and three across the top. You can then slide the top cover off.
The bottom cover just requires removing the visible screws and gently but firmly tugging.
The security thing is not bolted through the cover so it is probably stuck on with epoxy or cyanoacrylate. I think I'll leave it as the bond is very probably stronger than the fairly thin sheet steel of the case. I've removed the hemisperical plastic cover which makes it look less obtrusive.
It is similar to these "compulock" ones.
Acetone might remove the glue but it might also remove the paint.