More likely than not, the electronics inside were meant to detect the motion of the water. I'd be willing to bet there was something floating in the water that

More likely than not, the electronics inside were meant to detect the motion of the water. I'd be willing to bet there was something floating in the water that detected the motion of the water. Perhaps more of a vibration / proximity detector than motion detector, but that's what 'half empty bottle of gatorade and some electronics' says to me.