XDJM, help!

sold the item over $230 on June 28 in Amazon, buyer received on june 30. Today I received his email:
"Hello. I bought these binoculars from you through Amazon a few weeks ago. I was away on a trip, but just got back and finally received them. They were described as a new item on Amazon, but they are not new. They are clearly used and even have one broken piece on the objective caps. Also, they are missing the included strap. I would like to return these binoculars with full refund. Please advise. My contact details: E-mail: [e-mail]. Telephone: [phone]"

The item was brand new, I bought from Ritz camera and I checked it before I shipped.

This guy is lying, how can I do? any suggestion? thanks!