PayPal sided with buyer who returned a box of rocks

Sold a laptop for $640. Buyer claimed it didn't work and opened a return. PayPal required me to accept the return. Got the package back and it weighed 8 pounds. Original laptop was 4 pounds. Opened it and found literal rocks wrapped in newspaper. Filed a claim with PayPal showing weight discrepancy and photos. They said I accepted the return so the refund stands. Now I'm out the laptop and the $640. Police report doesn't matter to PayPal apparently. Anyone actually won one of these return scam cases or is it hopeless?