Why did the person get shocked when they attempted to move a car using a temporary button for the first time?

The person got shocked because they forgot to hook up a ground. In electrical systems, grounding is a critical safety measure that provides a path for electrical current to dissipate into the earth in case of a fault. Without a proper ground, any faults in the system could lead to live electrical components becoming energized, which can create a dangerous situation for anyone interfacing with the system.

When a temporary button is used to control an electrical device, and there is no grounding, the risk of electric shock increases significantly. This is because the user may inadvertently complete a circuit that allows current to flow through their body, particularly if they are also in contact with the vehicle or other conductive surfaces that may be at a different electrical potential. Proper grounding helps to ensure that in the event of a malfunction or short circuit, the excess current has a safe route to the ground, thus protecting users from electric shock.