Cracked glass/ Mcintosh

I don't have any experience dealing with an A-gon customer who claims the glass is cracked on a Mac integrated I sold him. I provided pics to him and the Mac was boxed the same way I got it from Mcintosh. Box in a box with it attached to the plywood. I find this very hard to believe.

What I'm wondering is how should this have been handled by the buyer. Shouldn't he be taking this up with the carrier? Btw, it was shipped on April 21 and just today he sends me the e-mail.The box was delivered 4/24 or 4/25. I'm just now finding this out. I also had sent e-mails to him asking if he got the tracking number and there was no response. Last week I sent an e-mail asking if he got the Mac and in both cases he never sent a reply of any kind. I need a little guidance on this.

Thanks to all