Yeah, when he was sitting at his table I'm thinking, "Man, what are those, like ten bucks? I have a giant screwdriver. I should try it out."

Yeah, that's how those things work. The play and record buttons click in, and then pressing "stop" pops them back up. That's also another reason Chuck flipped it to put in the batteries. Ernesto would have certainly noticed it and pressed the stop button first. It prevents wear on the tape.