What a weird message! I don't think it was necessarily threatening - I can easily image someone saying these things in conversation with their friend, or texting it and adding a lot of exclamation points and emotes - but there's an undeniable aggressive vibe. They're basically doing everything they can to threaten to return the item without actually saying so. That whole thing is SO weird to send to the seller!
And s/he comes off sounding like a complete idiot, too. Maybe learn to be responsible for the things you're buying, person?!