Cave Giants Dungeon Switches

[Humble_M]

Can someone help me? See the spoiler for full info! Thx.

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Please excuse the VERY crude map...I'm trying to get to the chest in the upper left room. I figured out what what switches "A","B","C,","D" do. However, I can't get past the barriers labels with the ?. This is what I need help on. I'm guessing there's some combo. also, I know that there are also switches in the rooms below the side rooms. Hopefully, this makes sense to someone! sorry, the two ? below C'/D' are switches, not barriers (which I also can't figure what they control)