Storage GNex won't charge, how to restore warranty

Hi, everyone
Since a couple of days I've been experiencing issues with my GNex. It won't charge even when it's turned off and connected via USB and my phone storage doesn't show on the PC. I searched the web but couldn't figure a way to fix it on my own. Now I'm interested how I can return my warranty because it has been rooted, it runs with stock but it has a different kernel. (I already found an app to relock my bootloader without PC )