By default the camera performs a sensor cleaning routine by shortly vibrating the sensor shift mechanism when it is turned off. This is not a malfunction.
However, if a strange noise or vibration is observed other than by this automatic cleaning, there may be a problem with internal parts such as the SteadyShot mechanism. Turn off the power, remove the battery, wait for a minute, then reinsert the battery and turn on the power again.
If the issue is still unresolved, the product may need to be repaired. If you believe this to be the case, please contact us for further assistance.