Sounds dodgy to me.
Anyone that knows what they’re doing should know how to clean previous usage off if they’re going to palm it off as unused. At least I’d want a load more off for that misrepresentation.
Or return for a refund - you are entitled since it’s not as described - and buy the one for sale on here from someone that’s in your neck of the woods … and you could go and have a look at it … Mavic 2 Zoom + various filters (For Sale - £800)