Chosen Solution
My first instinct is that it is just a defective part. Because the parts are fairly cheap and the repair not too delicate or time-intensive, I recommend giving it a shot. If you’re having any other problems with the camera, proximity sensor, etc then I would definitely blame the part. That being said, while you’re doing the repair you might also want to make sure that the glue on the screen for the microphone actually has an open hole in it for the sound to get through. You’d be surprised just how insulating glue/adhesive can be to a tiny a microphone. It wouldn’t hurt to blow some compressed air through the speaker mesh just for good measure while you have it in pieces. Now, if you finish the repair and still don’t have any Siri or Voice Dictation, then you probably have a logic board issue, and that’s definitely a repair shop thing (involving micro soldering).
Thank you. What I ended up doing was just replacing the entire front panel, where the mic and those little fiddly parts are already attached. It was much easier than doing the parts individually, and the cost difference was not much. So it’s been working perfectly since I did that.
