Transforming path to svg, how to animate the position of only 1 dot in a line?

Question

SVG

Good afternoon.
Please help me solve the following problem in svg.
There is a line that rotates at anchor point 400, 400 (the starting point of the line) by 30 degrees

<path d="M 400,400 l 0,-50 z"
        id="mp"
        fill="orange" stroke="green" stroke-width="1">
  <animateTransform
      attributeName="transform"
      type="rotate"
      from="0 400 400"
      to="30 400 400"
      dur="4s"
      repeatCount="indefinite"/>
</path>

Tell me how you can make it so that after the end of the animation, a new animation starts, returning the line to its original position, then the first animation starts again. You need to get about the same movement as the wipers in the car.