as I said before in the other thread, you CAN replace the shell but you have to be extremely careful. You can't just replace it sitting in your car, you need a clean table and tools, because as above video suggests, you will need to take apart the entire phone. It's not hard if you know what you are doing. If you've never replaced a screen on any of your phones, don't even try to replace a shell.
By replacing the shell, you will automatically void your warranty.