The watch is gen, at least the dial, bezel, hands, caseback, bracelet, crystal, DW - it would a very expensive franken and nobody would bother. I would NOT open the watch just to check the movement. It would void whatever warranty you might have and it would also compromise water resistance.
The case number should match the warranty card (mine does). Since the card is not dated you would have 3 years of warranty but I think you will have issues with the service center. I'd contact the seller and work this out.