Quoted from TheLaw:Welcome to node boards.
Unfortunately TheLaw could be correct.
Do the simple things first. Check all your connections under the playfield and make sure one of the wires has has not fallen off. The shaker on GB is violent like GOTG and could shake the connections apart. After that download the bulletin for GB and make sure your machine has the modification. https://sternpinball.com/wp-content/uploads/2018/10/Stern-SB188.pdf If your node board is fried, you can usually see it.
Contact a tech or Stern next. Good Luck!