I struggled with stopping play and returning to start for ages. In the end, it’s very easy.
- Map one button to control “play” and assign a #cc number (can be any number.)
- Insert a second button to control “play head position,” and create another #CC number. But this time, (very important), make sure the position slider is fully left and at 00:00 before learning. Now when you hit the second button, the slider will return to zero and playing will stop instantly, because there nothing to play at the zero point.