Could you have moved one of the displays (credit/match) to player 3’s since it sounds like it was the display itself and not the connector?
Regarding the match play, with that format (using games on the show floor) it is a crap shoot - but at least if you have a group of 4 all getting screwed the same exact way, at least it’s “fair”. A lot of issues at Pinfest that people point out and say “people bring machines with weak flippers, etc.” is actually power related. I was helping someone on a bank where instead of the 2x30 amp circuits in each main box were feeding 12 machines (6 on each) they had plugged in 5 or 6 power strips so they were feeding about 30 machines.
I purposely set up my 3 machines in freeplay on a quiet corner that had mostly EM’s on their box, figuring that they would draw less current, and I was right - I didn’t have any power related issues - no one on that corner did.