As you know the Limited Warranty for Intel® Server Building Blocks is a period of three (3) year after the date the product was purchased. However, this warranty is applicable after the date the product was purchased from an Intel authorized distributor. Is your e-bay seller an Intel authorized distributor?
See the Limited Warranty for Intel® Server Building Blocks document here:
Looking into your S2600CO serial number in our serial number tracking tool, I received no record returned. You can check your product warranty status here:
Be sure to select "Board or Other".