Thanks for the hint
I was more thinking along the lines of USB voltage, with the higher voltage of a standard USB burning out the circuits.
But that would have needed unnecessary exposition.
I thought about a give-away line that it's protected, which later turns out to be a lie.
But in the end I've abandoned that ploy altogether, and made the antagonist (the cat
) want my hero to read the contents as part of her cunning stunt.