On level 2, after activating 4 valves, the gates do not open. What to do?

so me and my friend have been stuck on the 2nd level for half an hour. does anyone know how to complete the first section of it? it would be really appreciated

Title.

You said on the store page that this game can be played solo. But does that mean that you play alone without any opponents? Or do you play the game against AI-controlled opponents?