If the Gravity Lift is fixed, use it to travel upwards.
I need a hint about how to search scenes.
You can show every hotspot by pressing the space bar.
I need a more explicit hint about finding the release for the Cargo Valve.
Travel up the Gravity Lift, then go though the door to the flight deck. You'll find what you need on the flight deck.
I need a spoiler as to the exact location of the release for the Cargo Valve.
To release the Cargo Valve, interact with the holo-panel. It is in the middle of the scene; a grey rectangle with large white button and six, smaller, red and white buttons.