I don't usually comment on these topics since eventually both have to come at mutual solution.
However i noticed that the seller hasn't posted a full picture of the board/ more pictures. At least not on this thread. If he had shared with the buyer then i apologize in advance.
I can see the crack glimpse already in seller's photo where
@Usman Raza showing damage. You can slightly see the crack already and board getting slightly colour change. See the top left in my attached image.
Usually i tell the buyer in advance if there is any damage, scratches. I sold a couple of routers and had mentioned the same on my thread. If this was the case then it shouldn't happen with any buyer as we all buy stuff from others as well.
And i mean i can be so wrong in this then i deeply apologize to seller.