We are confused as well without more information.

Yes, post a picture. Is that the only work you did?

Can't tell without a picture.

Problem with soldering to those old connectors, you just may not get a good solder bond, unless you desolder and scrap the legs a bit and the resolder. Or just install new connectors.

Yes, this seems like an issue still.

Sometimes though, I do see the wired connectors as issues and have to repin the ends of the wires. Can you move the wires a bit when the game is on to see if it clears up any of the displays?

During game play or just in attract mode? What are the sounds doing when you play a game.

Which connector and which direction is did you install it wrong?

What connector number is it? You may have sent a higher voltage to a lower voltage line. Likely displays and sound issue likely are related.

I would have to locate the drawings and review. Likely someone else will have some ideas before I can get a chance to review.

I just wanted to help get all the information as possible to help you get this repaired.

Have any other games with this board set?