I think he means trace the wires leaving the red start stop button to its 2 pin black connector, separate the connector and jump the two pins (terminals some call them ) and see if it cranks. When I say jump I mean connect those two wires in the connector that you unplugged. On most of my skis one wire is yellow, one is red. Not sure if same on yours but quite possibly.
This would simulate you pressing the red start stop button and closing the switch contacts inside signaling to spin engine over.
This test tells you the switch is culprit or wiring from switch to that black 2 pin connector under steering near front gray ebox that you just unplugged.
Rob