Then I tried connecting 3" jumper cables directly from the Yun to the 16x2 shield (on 5V, A4, A5, GND). This also didn't work.
TWI: 2 (SDA) and 3 (SCL). Support TWI communication using the Wire library.
I'm having quite the same issue with a no name "MPU-5060 type" sensor.
so i tested the MPU-6050 with a voltmeter and the i2c pins don't give anything out actually