On the Dominion website there are these "training videos"JPG which explain how their systems work: https://www.dominionvoting.com/training/index.html You can start each one of these videos and then save it with right-click.
Here's a low resolution 2 MB part (2:15 minutes) of the video "Democracy Suite® EMS Results Tally & Reporting", copied starting from 4:10 of the original file: https://files.catbox.moe/w8b4e1.mp4MP4 First is explained how the memory cards content can be uploaded. At 2:00 it gets very telling. That surely explains a major manipulation method which is probably the simplest one because it doesn't require fake voters or even ballots.
It's hard to believe that it ever was allowed to use such insecure systems.
And, what already what turned out to be a real problem is that there's no check implemented if the data of every memory card is transmitted. So someone can manipulate by omitting cards which potentially contain the votes for the the "wrong" side.
Surprisingly "Dominion Voting" claims that everything's fine with their systems: https://www.dominionvoting.com/
