This story somewhat mirrors a similar RMA experience I had with Newegg a year or two ago. I bought several high-end Cisco access points. One needed to be RMA'd, so I boxed it up and sent it back. The problem was that I inadvertently used the box from one of the working APs. The remaining boxes were discarded. Newegg refused to take the RMA because the serial number on the box's label didn't match the serial number of…
Nintendo was notably one of them in the past and so were some video card manufacturers.
Newegg didn't want to eat the cost of the return; and who can blame them?
When I handled returns for the electronics retailer I used to work for, if we didn't follow all of the procedures and meet all of the requirements for the return exactly, the manufacturer often wouldn't credit us for the return and would send it back.
On the other hand, sometimes we did eat the cost because the customer followed all the rules we told them about...