Sigh, somehow I knew selling a laptop for parts was a bad idea.
Buyer emailed me saying the battery was completely dead and it doesn't work at all. I replied telling him to plug it in and charge it.
Did he really think I left it charging for the past several months since I replaced it?! During the auction, the laptop powered up just fine and I even posted pictures of screenshots for some performance tests.
It would be nice though if USPS marked it as delivered so that paypal will release my money.
eta: He is now claiming the battery won't hold a charge and therefore that I misrepresented the item (in the ad I stated that it "worked great when we used it last a few months ago before replacing it"). The only thing I mentioned about the battery, was that it was included. It was a 7 day auction and he had plenty of time to email me asking about the condition of the battery, before he bid, if that is the only reason he purchased the laptop. Based on his auctions for sale, he obviously purchases laptops for parts, refurbs them, and resells them on ebay, so he's probably pissed that he didn't get a brand new battery along with other parts, to turn around and sell for triple what he paid.