How to open the Bluemont Manor Strongboxes

Solving the Bluemont Manor Strongboxes in Crimson Desert is arguably a little easier than the Hernand Castle Strongbox. After all, these don't require you to replicate a melody, but instead you have to mess around with an owl picture and some strange pistons. Though you won't need to get a key to access the room with the strongbox, you will need a mask to steal the items inside at the end.

I can't confirm this, but to gain access to Bluemont Manor, you might also have to complete the first...