*Make sure you have AntiVirus off as "mobile88" mentioned...also make sure in Settings | Security |Verify Apps is UNCHECKED! Google will block root process.
Used Root Genius on 503L B006, ran program, X1 restarted, then program says unsuccessful. I checked my phone and there was no "KingUser" in my Nova Launcher drawer, but KingUser did install itself as a systems app. Download Root checker from play store and confirmed that X1 is rooted, despite Root Genius saying it failed.
I downloaded SuperSU from play store and updated the binary, and uninstalled KingUser.