For me, captcha hell is very random, and when it happens, it's things like "pick all squares with stairs" where I have to decide if that little corner of a stairway counts (and it never seems to) or "pick all squares with motorcycles" where the camera seemed to have a vision problem.
What usually works for me is to close the browser, reload, and try again.
What usually works for me is to close the browser, reload, and try again.