You’ve dented your seatstay, but you’re talking about a warranty issue…I must be missing something?
That’s my impression too.
It either arrived at the OP like it or it has happened in between, OP which was it?
OP – if it came like that out of the box, you needed to return it for a refund at that point in time.
It looks like you’ve ridden it, now it’s impossible to distinguish between riding wear and tear and what may of been there out of the box.
If those marks weren’t there when you got it out of the box, you’ve put them there and don’t have a leg to stand on in terms of a warranty claim.