I agree with Frank. Make no mention of your previous experience. Walk in and state you received it as a present and it is defective and all you want to do is exchange it. If all the original packing is there and it shows no signs of not being purchased yesterday, there should be no issue. The person at the returns desk does just that, makes returns, not decisions. Give it a try and don't say anything about your previous discussions, etc.
"A hen is only an egg's way of making another egg".
– Samuel Butler