When you stop and then go to start the car within 30 mintues of when you stopped it will not start again. You have to wait and then it will start. This happens on and off and the dealership can find nothing wrong.
Three broad possibilities: fuel flow has stopped; spark has stopped; electrics have stopped. The fastest way to get closer idea is for YOU to do a little expermenting when it doesn’t start. Are YOU willing to do that?