From eBay's info page about the Money Back Guarantee (applicable if the buyer opens an INR request): "Generally, the buyer is responsible for accepting the item when it arrives. If the buyer refuses delivery, their claim is not eligible for eBay Money Back Guarantee."
https://www.ebay.com.au/help/policies/ebay-money-back-guarantee-policy/ebay-money-back-guarantee-pol...
A delivery attempt is (by and large) akin to 'delivered' by eBay, and not accepting the delivery or refusing to arrange collection or re-delivery should disqualify the buyer from being able to make a successful claim - however, if they do open a request, do not allow it to be handled by the automated system, rather, use eBay's call me back function (through help & contact) and explain the situation in full, highlighting that point about the buyer being responsible for accepting delivery and not doing so (which I assume can be confirmed through ebay messages) means they are not eligible for an MBG claim.
Even though you state no returns, you will still need to determine how to handle the return, so at this point you may be able to resolve the situation before any requests are open by clarifying to the buyer that you don't actually accept returns but as a goodwill gesture you're willing to provide a refund of the item price once you receive it back (keep in mind if you have to contact ebay about this buyer, they will look at your message history, so I recommend being firm but fair, polite and professional, and approach it with the sense that you're helping the customer as much as possible, just without their change of mind costing you unrecoverable money).
