he did his part...you got the money.

Originally it was your mistake that prevented it from being delivered without a signature...the post office may or may not have left notifications, and escalated the mistake.

Would you leave positive feedback for an item you didn't receive?...I wouldn't.

In his position, I'd be upset, too.

Honestly, I think you should send him the chip...and maybe even a partial refund, and hope for the best. Really great customer service goes a long way.

Sorry...I know it's not what you wanted to hear . I've never sold a thing on ebay, so this is strictly a buyer's opinion.