When you sell things such as electronics, the money goes into pending status. Typically, there has to be proof of shipment for this to be released into your account. Anyone who has sold physical electronic goods on eBay is aware of this. Now, you can get the money into your account without shipping confirmation.
Just send them anything over a penny back as a refund. Call it a "good buyer investment" if they ask. It will show up as a partial refund to PayPal, and any money from that transaction that was pending and locked will immediately unlock and go into your account balance.