Jim GM4DHJ ... submitted this idea :
this new motorised roller shutter doesn't seem to have a lock...is that OK ?

If you mean shutter on a door, you should find that as it closes, the
barrel should continue a little further than needed to actually close.
Hinged plastic link sections connecting door to barrel, then are
partially inverted, so as to jam or lock the door down. My 2m wide door
has four of these plastic hinges, spaced along its width.

The only way the door can be then lifted, is by turning the barrel, or
by forcing the door and breaking the plastic hinges.