I believe that even through a text-only terminal, a superintelligence could do anything to a human. Persuade the human to let it out, inflict extreme pleasure or suffering with a word. However, can't you just... limit the output of the superintelligence? Just make it so that the human can say anything, but the AI can only respond from a short list of responses, like "Yes," "No," "Maybe," "IDK," "The first option," "The second option," or a similar system. I... don't see how that can still present a risk. What about you?
In theory, possibly, but it's not clear how to save the world given such restricted access. See e.g. https://www.lesswrong.com/posts/NojipcrFFMzNx6Grc/sudo-s-shortform?commentId=onKfTrunn2Q2Gc4Pw
In practice no, because you can't deal with a superintelligence safely. E.g.