Um... can we open the trap a tthe back left corner, but not go down yet in case there's no ladder?

>can we open the trap a tthe back left corner, but not go down yet in case there's no ladder?
Unfortunately, it's the other way around!
There's some kind of access shaft in the corner of the room, complete with a ladder set into the wall, but it's barred off and Ruby can't fit through!

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