That’s why it doesn’t work like that. The voting machines each have their own count and are not connected to anything, not to each other, or a central system.

At the end of voting day each prints a tally of votes, that is both sent to the central counting, and displayed publicly so that the citizens can cross-verify that the official count is correct.

And as I said, there are multiple systems to guarantee that individual machines, or batches are not tampered.