Costco will definitely give a full refund. If the scanner was bought at Costco, you could return it even if it was over a year old. I think the only criterion Costco goes by is if the model number shows up in their computer.

Costco returns the item for full credit. There's no loss to costco.

I'm too embarassed to relate my own costco story but, if they gave me a full cash refund, you will have no problem getting a refund. I got the HP ScanJet 5200C.