Hi all,
It's been quite sometime since I'm stuck at the mechanical door in the cave under Elion island. I tried sticking one of the boxes in the mechanism in the hopes that it will stuck the mechanism and it will finallly break but that did not happen. Looking forward to know more.

Sorry, I don't quite remember that part. Could you post a screenshot maybe? Been a while already since I played that.

This is where I meant. It's also known as the water pump chamber.

Hi Jivan28! You almost got the solution yourself. ;)

SPOILER ALERT:

You need to put the box just a tiny fraction to the right (on the other side of the narrow metal part that touches the right side of your cube on this screen). After that the cube will keep the arm of the mechanism from rolling back inside. Hard to explain with words, but if you need me to, I can go and catch a screenshot. Did you get it?

It would be best if you share a screenshot sir, thanx.

Here's a screenshot of the solution. See, you almost got it by yourself! :)