Remove your additional switch because you have build a short with 5V on the wrong line!!!
I have destroyed my PCB like that! Have made the same things you did! Needed a freeplay coin switch outside the cab and killed my soccer.
Have seen the same distorted screen when i pressed the switch.
Connecting an extra switch parallel to the coin switch, will not work on this old soccer.
No problem with newer PCB and cabs but this one has a different setting!
Got my soccer PCB repaired by a trained technican, now.
P.S: Do you need the other picture of the start button (on top)?? We send you the pic from the side with the type and numbers before.
Please give me a note when you find the circuit diagram or other info related to this game.