Locked door on level 11

[Kiwi]

This has been driving me nuts for awhile now, so any help is appreciated.

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In the Room of Levers (Upper left) I've fallen through to the room just below through the pitfalls, there's a pair of locked doors in the upper right, with the one on the right side with a blue aura. I've mapped out every single pitfall in the area, and none take me to the other side of the door. I haven't been able to find a switch either, so I obviously missed something.

I did go on to the later levels skipping over that door, but locked doors irk me quite a bit.

Another side question, on the final corridor on level 9

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Is there any way to get back to the main level? The wall there closed when the ogre came, and I can't find a switch to open it back up again. So I can't go exploring higher up

Edit Update:
Found the solution!

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I feel like an idiot I thought I had all the pits mapped out. If you fall in the one opposite the far one that drops you in front of the door (just south of where you have the I tile deep corner) you can find the spot. It's a bit south of the east most pit.

[DCJerboa]

Your first question... join the club; that's how I ran across your question... I'm looking for the same.
EDIT: H'okay... level 10, the area with lots of pits... drop down the second pit closest to where you enter the room. All other pits don't help, except the one I identified. (Found elsewhere on the forums)

Second question... there is a button, a corner or two prior to the wall blocking you from backtracking. I believe its on the outer way, a corner or two from where you are blocked. Look again. I just backtracked from the last level to the first room, so it can be done. (only parts of level 4 cannot be re-worked due to blue transporters having disappeared upon solving the level - so secrets contained therein you've lost the opportunity to complete).

[sevtai]

(only parts of level 4 cannot be re-worked due to blue transporters having disappeared upon solving the level - so secrets contained therein you've lost the opportunity to complete).

Preety sure in one of the side rooms the scavengers come out of, there is a lever to turn the portals back on.

[Kiwi]

Found the solution, I updated the first post with an edit adding it.

Thanks for your help on level 9!

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So glad I can go back and explore the rest of the game now. Yay!