Grimrock

I am stuck on level 2 and need a nudge or some guidance on what I am missing. I can see the big blue crystal behind a gate which is closed/locked and unfortunatley I am unable to proceed any further since I cannot find the other key.

There is also a cell area with a bag and 2 buttons but not sure if this is something that needs to be solved later on since those doors are all closed.

Thank you

Try pressing one of the buttons, then look around. If you have trouble figuring out what changed, press the button again.

Thanks good clue.... will look around more!!!