If a ship equipped with Advanced Sensors (e.g. Wrenbat) dies an action that yields stress before revealing a dial (e.g. Hux), what happens if he then reveals a red maneuver (e.g. full stop)?

1). Completes the maneuver and gets 2 stress, or

2). Does a 2-forears white?

It does a two straight white

Yup. It is stressed when it reveals the manoeuvre so it's replaced with a white 2 straight.