The easiest way to physically deactivate the on-board MIC is to plug another mic into the external mic port. If that mic has an off switch, there is no physical way to record anything with MOVI. Alternatively, just plug an unconnected (cable end no-where) headphone jack in the external mic plug.
I am surprised to hear though that MOVI picks up noise from the onboard mic during non-talk phases. Do you have more insights into that by any chance? I'd like to take a closer look if it's possible.
Thanks for the reply. I've done all that you've mentioned above. I've done some test with an external mic connected and the push and play button not depressed. After a few minutes of casual conversation, room noise and white noise, MOVI will say, "Sorry I can't hear you", or another default statements that reflects voice activity even tho there is none. This is why I've concluded that it may be the on board mic picking up some kind of noise.