my phone still covered if have cracks on back

Today, my phone suddenly froze and so then I decided to restart it by pressing the home and sleep button at the same time. I was expecting the Apple logo to appear but it never did. I've tried a bunch of things like putting it on recovery mode and so then I just gave up and decided to bring it to the Apple store since I'm still under warranty. Do I still have to pay for the repair for the crack or is it covered since before this, I had no problem with the function of my phone. If not, is there any other way I could possibly turn my phone on? HELP PLEASE