You have to change the numbers in the database with something though. Either you are going to use faked or stolen credentials, which is easily identified and traceable, or you have to inject something into the software to get it to change the values which will again be obvious.
Successful hacks either pull data or break it. A hacking attempt will only be a secret until someone starts looking for it. Given the scrutiny the voting machines have elicited lately I don't see how it wouldn't be spotted almost immediately. For instance when the Russians hacked Clinton's emails they just pulled information. They couldn't go in and change things with no one the wiser.
Chaos like setting up meetings between certain politicos with known suspicious people to make it look like there was collusion going on even if none existed?thoreau wrote: ↑20 Sep 2018, 20:324) You yourself have said that Putin's main goal is not to get specific policies implemented by US leaders, but just to weaken the US with chaos. Well, imagine if on Election Night a state is called by 10,000 votes and then a few weeks later it is reported that 12,000 provisional ballots have to be counted and just about all of them are from Democrats. Some Americans would, of course, see this as a conspiracy against Democrats. Others would see it as a conspiracy BY Democrats. "They must have done something fishy, no way that 10,000 Democrats just happen to have paperwork snafus but hardly any Republicans."
That's a trolling success. That's chaos. That's a massive headache for the next administration's legitimacy.

That's a completely different scenario that doesn't really have anything to do with voting machines. I can honestly say though that I have no idea what Trump would do given he has the attention span of a goldfish.