I DON'T UNDERSTAND IS IT TRAPPED OR ATTACKING?.
OR THE CHEST ATTACKS AND SHE'S TRAPPED INSIDE?
She's a mimic, pretending to be a treasure chest to lure in her prey, though she’s not looking to eat them, she’s after... entertainment. The mini-game is basically foreplay. If she likes your lockpicking skills, you’ll get to open the final lock. If not, she’ll be the one using her key.
At the end of the mini-game, there will be a victory scene and a defeat scene, though they’re not ready yet.
The part that breaks is actually part of her outfit, but it can also be interpreted as her being trapped. I might give her a little redesign