Grove MOSFET switch always on

I am trying to power a pump using grove PI, and a grove MOSFET switch. The switch is always on and doesnt turn off. I am using an external 12V DC power supply. The moment I connect the power source and the pump it turns on, even if its not connected to grove pi. When I connect it to grove pi its the same thing. Its just always on and doesnt stop even when the you close the switch.

Any ideas of what could be happening?