Somfy shutter motor halts after brief use and recovers later, normal?

Not normal, though it is a built in safeguard. The motor's thermal cut out stops it when overheated and releases once it cools. The trigger is generally extra drag: a bent or heavy curtain, grimy guides, a stiff bearing, or a motor undersized for the shutter. A hot, sealed box makes it worse. We locate and remove the drag instead of simply swapping the motor.