Can you try the 410 with another head? Also, do you have access to another cab to try with the xs400c? You want to work out if the problem is with the amp or the cab.
i dont have another cab, but i do have another head...a xs400 (exact same one as in the combo, just with handles)lol.
the 410 works im sure of that, because ive tried it with the xs400, its just when i try and run the xs400c with the 410 i got no sound