Your switch under the trunk is bad. I just had the same issue on a service call. It would score the key letters, but never open the trunk and go to heart multiball. It would always let the ball out on ball search. The switch takes a beating the way the ball comes to it. Replace it and you'll be good to go.
You'll just have to look at the plastics and the trunk to see how it comes off. Not too bad.
Good luck.