Had an issue like this as well after changing a bulb, I shorted something when a wire touched another. Was the power on when you changed it? I learned to get the power off no matter what I do below the playfield.

Check this item on your board (just took an image of the internet), when I remember good it is one of two on the top. There is a special way to check these as the current flows only in one direction. Think on PinWiki there is more info about it.
10734.jpg

I'm not at all good in electronics so changing was something I needed help with. Desoldering it from the board and solder a new on on it solved the problem.

Hope this helps.
Peter

Thanks for updating my comment. Think I mixed up this repair with another mistake I made along the road.