And it's unknown how many other votes it may have changed:
The problem occurred at the Craft Recreation Center in Greensboro Wednesday morning. A voter intended to vote for Kay Hagan. But before he pressed the vote button, it switched to Thom Tillis. He tried again, and the same thing happened.
The voter then alerted poll workers. Guilford Elections Director Charles Collicutt says they re-calibrated the machine and now it is reporting as is should be. The error with the Craft Rec Center machine is the only one known to have the problem this cycle. He says there’s no way to know for sure how many times such an error has occurred.
There's one way they can check: Check all the votes for that particular machine, and if a voter chose mostly Democrats in other races but also voted for Thom Tillis, there's a good chance that Tillis vote was incorrect. Especially after what happened with the Pat McCrory fiasco, I doubt there's many crossover Dems voting for Thommy Boy.