The Dallas Morning News does some good reporting on this one.
1. Regarding being hacked by Putin or whatever, electronic voting machines aren't connected to the Net.
2. Regarding being hacked by Diebold, generally, observers from both duopoly parties are at polling places. (Let's hope that third parties get enough membership in more places to do that.)
3. Votes in Texas are then manually audited.
That said, while half of Texas counties use machines that produce paper vote printouts, that means half don't. Beyond the issue of hacking, machine error happens and without that paper trail, it can't easily be investigated.
This is the type of thing that something like a Brad Friedman of Bradblog should be reading, then honestly trying to refute — if he can. But he won't.
Don't know about all people claiming vote hacking conspiracies, but I do know that he's a JFK assassination conspiracy theorist and probably has one or two other conspiracy theories in his woodshed.
As for "vote hacking" in general? Good old fashioned vote fraud may still happen somewhere. Contra GOP wingnuts, I'm not talking about individual citizens voting illegally. I'm talking about local officials corrupting the process.