[Sans Peur]

That is a resetable breaker. If it is tripped it will be sticking out. If sticking out push it back in and see if the seat works. If it isn't sticking out then its not tripped and there is probably a connection issue somewhere.
First make sure you have power at the breaker and start tracing it from there. Power should flow from the breaker to the switch to the seat motor. If it is getting all the way to the seat motor, then it needs replaced.