Package out for delivery - Buyer didnt pick it up

[Blasko]

Dear fellow Sellers I need some advice from you. This is the first time I am facing with this problem.

I have sold item worth of 750$ and I send the package day after the order has been placed.
Item arrived, it was Our for delivery (Delivery attempt) but Buyer was probably not at home and the Notice was left to pick it up in Post Office.

I was contacting the Buyer but he is not answering. If he dont pick the Item in a few days it will be returned back to me.

What to do in this situations? Do i need to do Full Refund if he dont pick the item after the Item is returned to me?

I have read somewhere that I am not obligated to do refund since "Delivery attempt" in eBays eyes counts as "Delivered" since I have done everything as a Seller?

Please advise, thanks in advance.

Best regards.