"The machines were not rigged" is the same kind of statement as "covid was not created in a lab". You can't be 100% sure that it's either true or false. If they had some cheating going on in the machines now they've had more than enough time to scrub the evidence. You'll never know for sure. The paper trail is there so that can be analyzed, but what happened inside the machines cannot be proven in posterity. However if you have the machines set up for fraud it takes as much effort to change one vote as it takes to change 100 million. That's why i personally seriously doubt noone even tried to get into the machines and had success, wether they had success in the election itself or just in a controlled environment we'll never know, but voting machines are nevertheless a huge liability that have no place in democracy.