What are the numbers on that sticker ont he decoder? Also, along the edges of it, it should have an ESU part number. I can see on the side nearest the camera it says ESU and then something on the edge of the board.
Sounds like it was new in the box, although that wouldn;t stop an unscrupulous seller from swapping parts and resealing. However, that vendor has a very high rating so I doubt they are doing any deliberate cheating. Could be you just got a bad one. Did they throw in any sort of cheat sheet with the functions? Most vendors have at least that much, so you know what button does what. It is entirely possible that Intermountain set up somethign other than F8 as the sound on/off - Loksound decodes are extremely customizable that way.
Though I see he doesn;t always edit his auction text. The long descriptive paragraph says it's BNSF, but the lead sentence and the picture, and obviously the one you actually got, is the NS LV Heritage unit.