MB Quart Head Unit

So we bought one of those MB Quart Marine CD players on ebay, and after we get it hooked up we have no sound and the face won't open. The unit powers on and everything and we can cahnge modes and what not, but like I said, no sound, and the motorized faceplate doesn't open. So we call the tech support line that the seller told us to call, because the thing came with a ninety day warranty, and they tell us we need to check the voltage with a meter. My question is, how would voltage effect the ability of the unit to open? I could see how maybe the internal amp wasn't getting enough power or something, but it seems strange that all the other functions work and you still can't open the thing. I don't know, we are going to check it out anyway, but it seems like it won't fix anything. Any advice from the stereo guru's out there? Hopefully we can figure this out fairly quick because there is only a month left on the warranty.