iphone 5s back camera wont open?

I got my iphone awhile ago and just recently the rear facing camera wont open. when I try clicking on the camera button it starts to open it but then glitches and goes back to the home screen. It's the same when i try to take a picture from messaging. And when i open other apps (like snapchat, instagram, camwow, etc..) it goes to the front camera and the button to switch views is gone...?? I already did the "restart, reset, restore" thing and that didnt help. I also tried deleting all of my apps and restarting again just to see if it worked, but nothing seems to be fixing the camera. I have a warranty on it so i can exchange for a new one but where could i do this?...Oh, and if i try to open the camera from the lock sceen by sliding up, it just goes to the white screen with the black apple logo in the middle (what it looks like when it turns on)