They can also be unlocked by pulling levers found on the floor somewhere. Of course, the game doesnt tell you that that's what the lever did.
I get the feeling that sometimes, you have to pull more than 1 lever. But in general, I was able to open such chests by switching once all levers on the floor.
You open them with levers. The specific levers,when you click them say nothing of what happen in the log and you can click to use them more than once.So there are two positions for this "special" levers, ON and OFF, if you pressed it more than once and forgot which way was the ON mode,then you need to check the chests and then go back and click the lever again.
