I agree. Like the family acting as though Ciara cured cancer because she opened the time capsule that could've clearly been opened with a small pry-bar or a even a heavy duty screwdriver. It was hardly a complicated box to open. I still go back to the absurdity of Alice hiding it in the chimney of a working fireplace. Please.
Would've made more sense that after the fire if they had found a little hidden niche within one of the walls or floor instead.
And no, there is no explanation as to how Ciara managed to open the box (that you can see is just a regular locking metal box, not a complicated puzzle box).