Check the ground wire connection. It's possible there's a break in the wire, or the crimping to the QD isn't right.
Would it matter if I cut the end of the ground chain off? The JAMMA harness' ground daisy chain had about 25 ground terminals and I cut off the end of the chain I didn't need.
Also, newbie question, what is QD? Quick Disconnect?
Lastly, my JAMMA harness has "quick" connect terminals, as seen below, and while they are quick to connect, they are a royal PITA to remove. I connected everything on my workbench to ensure everything was working, then I disconnected all of the wires. A learned mistake, as most of the connections were so hard to remove I used a small screw driver to pry open the terminal a little bit to avoid breaking off the post. Is there good/easy way to remove these quick terminals? I had to crimp many of them back into shape before putting them on, and I likely didn't get all of them into the best shape.
My connections, as they are now. Is the spacing of these contacts good? I watched a lot of videos on how to get these correct and adjusted all of them to around ... ~4mm apart.