This happened to my wife in 2016. The machine switched my wifes vote from Trump to Hillary. It did it a second time and she called the poll worker over to witness and that time it worked. A person has to carefully review after you vote to make sure it took the first time. Yes, she was ABSOLUTELY sure she voted for Trump and that it switched it.
Democrat election stealing has been going on for a very long time. The stolen 1960 Presidential election was the root cause of the JFK and RFK assasinations by the Cosa Nostra. And one could probably make the case that election stealing and killing in the name of it has been going on for a very long time.