I sold a working bare motherboard to a buyer with only one previous Ebay purchase at the time. About a week after delivery he said it wasn't booting and claimed a full Ebay refund of  purchase price and postage.

The buyer returned the motherboard, and on inspection I found the "CMOS Clear" jumper had been moved from its normal Pins 1-2 position, where it was when I posted it, to Pins 2-3, which all manuals say will damage the motherboard if booting is attempted while in this position.

I showed my partner, photoed the  changed jumper and some bent IDE pins, put  the jumper back in its normal position, and retested the motherboard. It wouldn't boot. 

Then I emailed Ebay pointing out the changes and damage and included photos.

Today Ebay have told me they are ordering a full refund to the buyer (including the postage I've already spent to send the motherboard to the buyer) and PayPal will enforce this with a charge on my account.

What can I do?