The failsafe circuit to protect against this (over voltage condition) is maybe $3 and incredibly routine in anything with power. I would bet everything that it is in there.

What's most likely though is that the fuse is also internal, and externally the unit will appear bricked.

While in general most parts will work beyond their ratings to at least some degree, this isn't really a safety margin. A safety margin is known, rated, and validated, and usually a property of a system as opposed to just one part within it.

Your safety margin is my profit margin.

- Mr MBA