Enable Samsung Galaxy S4 USB Debugging
1. Select Application > Settings.
2. In the upper-right corner of your screen, tap More.
3. Navigate to the bottom and select About.
4. Now, scroll down and tap Build number several times until you see a message that says “Developer mode has been enabled“.
5. Tap the Back button and you will see the Developer options menu under System, and select Developer options.
6. Check the USB debugging box under Developer options and you are ready to use your Samsung Galaxy S4 in debugging mode.
然后用 Kingo Android Root http://www.kingoapp.com/android-root.htm