fastboot works, adb doesn't
You may need to enable USB Debugging enabled

To enable follow these steps:


Open settings  
Open Info
Find the Build Number and tap on it alot until it says You are now a developer!
Exit Info
Open Developer options
Tap on USB debugging
Tap on OK


Notes:


In 4.1.x and before skip steps 2-4
In 2.2.x and before goto Settings->Applications->Development->USB debugging