Telling a laptop to shut down is very different from telling it to shut up or just shut. Shutting a laptop doesn't shut it down (at least, not by default).
There's so many grammatical definitions for both words I feel like there is a logical combination that makes it not redundant. With that being said they do both have I wanna say the same transitional verb definitions but both might be post-derivstive of "shut down."
That depends on the direction of the opening. Shut up means basically the same thing as shut down, but the hinged part operates in the opposite direction.
Yeah, just shut works for either. It's less so redundancy and more specificity.
If you think about it, there's only meaning with a frame of reference. Shutting up or shutting down could be nonsensical in the Void, as many things would be, I imagine.