Buyer returns a computer damaged laptop

Yesterday I received an computer laptop as a return from a buyer and the laptop was clearly damaged. The laptop looks like it was dropped and is definitely not in the same condition as when I sent it to her.

Also, for return shipment packing she placed the laptop inside a thin express mail paper envelope and then put that envelope in a box loose. There was no material to cushion the laptop such as bubble wrap or foam to hold the laptop while it shipped. It was just loose in a cardboard box.

Since she opened two disputes, on on Ebay and one on PayPal I called both. PayPal told me to fill out an IC3 Crime Complaint as part of the dispute process, which seems a bit odd since the damage might have occurred due to her packing. Or she may have dropped the laptop before opening a return, and intentionally used poor return packing to disguise the fact.

Either way, what is the general policy sellers should follow when a buyer returns expensive electronics such as a laptop computer and uses obviously improper packaging for those items? Also how should sellers expect PayPal and Ebay to handle disputes like this?

Edit: A small note. The buyer filed a return claim well after the 30 days of receipt of the laptop. The return policy listing on my auction was 30 days. And after a few excuses on her part ("I was moving and didn't have time to use the laptop") I finally yielded and allowed her to return the item, but I didn't expect it to be returned damaged.