the video? (see link below... start at the 6 min. mark)
Check out how they can insert an infected card into a voting machine & infect it... and any other cards inserted into the machine will also be infected and can pass it along to other machines.
But if someone broke into, or had a key to get into a room with the voting machines could quickly infect many of them in short order. It took them less than a minute to infect a machine even when they did not have a key to open it. 20 minutes... 20 machines.
One person could infect the entire room full of machines without anyone else being the wiser.
That person could be the janitor, or a maintenance guy, or a programmer or whatever.
If that person required someone else to give them a key or to pick the lock or to re-aim or pause a security camera then it would be a two person conspiracy.
Another possibility would be someone infecting one or more of the cards used on the machines.
It would NOT require everyone in the precinct being in on the scam. Here's the video link:
https://www.youtube.com/watch?v=GaLyth-08Hg