What helped me on the buttons (hard to hold in place) was a piece of tape on the outside holding them in place, while I "played" with the LEDs. What I saw when I first opened it up, was totally unexpected. Such is life.
I just held it facing down, but then I work on strange gear for a living. As long as you don't DO anything to the preamp there is no reason to void a warranty. Mine had no sticker, I think that I read that earlier ones had tamper proof labels, but I believe that someone said that Schiit relented about voiding warranties, but since I can'tsay that Schiit said it, don't count on that being true... It is difficult to imagine that they would void a warranty without evidence of real tampering. Looking something over and tampering are not one in the same things.