The attacks on the voter rolls are well known and documented, the Russian-GOP noise machine loves turning the conversation to "hacking the voting machines" themselves becaue it creates confusion. As far as we know publicly, the Russians accessed the voting machines, but didn't change anything, possibly because it was too risky (many states keep a paper trail of electronic voting), possibly because only accessing them and not changing anything would add more to chaos and paranoia. Much of their action has to do with undermining our confidence in the system, it's as much mental as it is for material gain (getting hte Magnetsky sanctions lifted)