Deduct on return for possibly faulty return?

[jahood1984]

First , I offer free returns for 30 days.

A buyer bought a CPU and opened a return stating the motherboard was faulty (I didn't sell him a motherboard), the return reason was ordered by mistake.  They added the faulty motherboard reason in the return message and sent me a separate message stating the same thing.  I responded and asked if they tested it in a good motherboard before returning it as a faulty motherboard may have killed it and I no longer have a way to test it.  They didn't respond so I sent a follow-up 2 days later after return tracking moved stating I'd take that as a no but they weren't hesitant to send me back a known if operational part and lied about the return reason.  Can I deduct 50% or anything at all?  I hate to relist it and pay to ship it a 3rd time to a new person just to find out it is dead after all.  Any thoughts on how to proceed, the buyer obviously doesn't care... 

[aproudparent2010]

If you don't give them a full refund they can actually report it to eBay and get the rest refunded anyway.

We had a buyer send an item back that was totally ruined by them and we deducted 50% for item being damaged and used.

Within a few hours they reported it to eBay and they got the other 50%...eBay said we could report them for misusing returns and block them but that was about it.

[jahood1984]

I've used the deduction before so I know they just have to complain and eBay will cover the over half but at least I'd only be out half the sale price and the item.