The S30 contains a Safety Interlock System that won’t allow the machine to run if it senses that the container is not properly attached to the motor base. See instructions for how to properly align the container with the motor base.
FAQ - S30
Either 1) the container was lifted or rocked from the motor base during blending and can quickly be reset or 2) the motor has overheated. Turn the dial to the Stop [○] position and allow the motor to cool for about an hour. Follow these S30 blending tips to avoid overheating the motor in the future.