I would just like to say that you have more flexibility with returns/exchanges with a lot of vendors than you do buying directly with DJI from my experiences. Don't feel like their NIB stock is different in any way either.
Where did you buy it? I have two P4s. One from DJI and the other from B&H. Both were sealed and all of the items were in their protective packaging. I really doubt that yours came from DJI with a used taste.
I have a total of 4 units. The first one I purchased though, was sent it to DJI Europe because of the defective gimbal, just received it back from the DJI Netherlands, and it still has the same issue.
I have purchased the last one from Baltic Mobile, and they refunded the money. All the Phantom 4's I've got, were new, sealed, and unacctivated.