This device was purchased from an official reseller and had not been used by anyone else before. It came in a brand new, unopened box and was completely sealed.
If that's the case, then you are lucky. The possible thing that I think why your wallet has a balance may be because someone accidentally sent a BTC to that wallet.
Sample I sent BTC from my 1st BTC address to my 2nd BTC address but I didn't receive anything until I realized that I sent it to the address with an extra character or missing character it might be lost forever if no one controls that wallet or someone lucky generated a wallet with a balance similar to what happened to yours.