I can think of excuses but not valid reasons.

If box is damaged, don’t send product to customer who paid full price. List the unit as Grade B with discount.

However manufacture date is 2017-09. I bought in 2018-05. With the high turnover of Banggood and this item in particular (Sold: 25042) that is highly unusual. This suggests to me that if the unit is genuine (which I cannot be sure since the box & sticker is important part of authenticity process) the unit is a customer return or refurb or something of this nature.

In any case, I paid full price for a new sealed unit, I did not want a refurb, customer return, fake, anything. I bought it as a gift and I simply cannot give it in the present condition. Maybe it varies by country but in my culture it would be considered rude to give an open/unboxed item as a birthday gift. The recipient might think I am giving him something I have owned and used personally for some months like a cheapskate !