@Katala I think I've got this hole plugged now. I need to figure out a more efficient way to do the double detection here. I have detection shut off when you get hit by an enemy which is causing this problem.
And here is the way to the key - its at the bottom level near the start before you start climbing up towards the first set of miner skeletons. Punch the wall a few times.
The little old man in the cloak before the door is suppose to show you where the key is and point you back in the other direction, I haven't decided on how to handle the dialog boxes for things like this yet. The man is animated but the event sheet isn't there yet.