Swap it out now while you can. You shouldn't have these issues on a brand new device.

 

Try removing and replacing the battery cover first: The bottom goes on first, so it should actually be the most secure. If there's nothing wrong with it, it will indeed flush. The bottom sort of slides on, instead of snapping like all of the others, so I'm guessing this is where the problem lies. Either it isn't fully on now, or someone did it wrong before and has damaged it in the process. If it doesn't go on cleanly, take it back.

The Volume button is built with a bit of tolerance in it, likely on purpose to prevent it jamming. If you try and push/pull it around much, you should notice it is actually quite stiffly in there...it can just move around a little bit. It shouldn't really rattle though.

 

My toilet flushes better then my phone back but I can live with it

 

Indeed. I have to shake mine pretty violently to actually hear the volume button and I have really good hearing.