To help frame the problem, I have written the following scenario:
It's December 19, 1972 and the Apollo 17 has returned to Earth, but something went wrong and they landed in the middle of the Outback. Luckily, I happened to be nearby with my ute and some common (rural 1970s Australia) supplies. For some reason, NASA is not here. I don't know why, and I don't have a way to contact anyone because my bloody radio is cactus. The astronauts haven't opened the hatch yet, and I'm worried they may be hurt. Driving to get help might take too long. Without any prior knowledge of the capsule design, is there a way I can figure out to open the hatch just by looking at it?
This fictional scenario is inspired by this comment.