I wouldn’t be surprised if they repackaged a returned unit as new, TBH. I’ve had that happen to me with Best Buy a couple times.
Most obvious of those two was when I bought an external WD 2TB drive. Got it home, plugged it in to format, and found it had already been wiped and connected/setup with a DVR device. It had a bunch of DVR-related files and directories on it. Double checked the serial number at WD’s website and found it had been registered 3 months prior.
I took it back and luckily the customer service rep that helped me with the return was the same person that dealt with the initial return the day before! Turns out they process the returns, and if it’s computers, it goes back to the Geek Squad area, where it then gets added back to the shelf for sale at a discount as “open box” (which, in my case, obviously did not happen.)
They apologized to me, asked if I wanted to exchange or refund (I refunded.) Apparently, the lady that returned it made up some sort of BS story about how it was originally bought as a gift, and was never opened for those three months.