A:AnswerYes, I was able to upgrade and pay the difference of current price. In fact the current price was a sale price so I was able to get a good deal.
A:AnswerThere is no need to register the product anywhere. Just make sure you either hang onto your receipt. If you purchased it with a My BestBuy account at check out in store, or online, it will be in your recent orders.
A:AnswerI had a similar issue with a Fossil Sport smartwatch. I figured out that via forums a trick to turn it back on, but I'm not sure how to fix it for a Galaxy Watch.
I would suggest contacting Samsung's support directly, visiting their forums or visiting Reddit to figure out how to resolve the issue.
A:AnswerIt’s active the moment you pay for it. No extending it. By the time you’ve had a watch for two years anyways it’s going to be time for an upgrade