Zero Escape 999: Steam Engine Room

Full video walkthrough guide

Head up and go through Door A. Then go through Door B. Check out the pulley and remove the wheel. Now go back through Door B and then go through Door C. Put the wheel on the pulley over here.

Head back down to the ground floor and check the box you have just lowered near the conveyor belt and receive control panel for something.

Put the control panel into the box next to the belt and the coal will be released. Collect the box filled with the coal.

Put the coal into the furnace.

Head back up the stairs away where the control panel is and slide the slider down to activate the boiler.

Pick up the 3 discs from the Gold, Silver and Bronze wheels.

Head up the stairs on from the other side near the 2 boxes. The stairs can be a bit tough to find since they look like they are the same but its actually different.

You will see stand where you can insert the 3 discs. Rotate the discs to the correct spot to unlock the door. The discs should be place in the same spot as where you found them. Rotate them to form a red star symbol in the center. The door is now unlocked.