I have Yun connected with Motor Shield. I tried powering the MotorShield with 9V battery and Yun from Motor Shield.
However, as soon as I connected the battery, the Linux environment stopped working. The Arduino environment is up and is functional but the Linux environment is completely dead. The power LED is not ON either. I tried using YunSerialTerminal example but that also left me with black terminal.
Have I burned the 3.3V regulator?