There is also another path that I found, where you can use the Star Valve on the Pentagon slot to drain the water. Took longer for me to figure that out in contrast to using the Square/Diamond Valve on the Diamond/Square slot.
Sorry for the late response. Its been about half a year so I might misremember some part, but it should be the one you get after solving the room where you need to push the box. It should be the same room where you find the key hidden in one of the bookshelves to unlock the gate for the extra fuse.
