I saw a blog about this and they said to check that date and time correct and then restart the phone. i would be interested to find out if this is the cause of this problem.
I assume also from because they dont comment on the glass that it is the same as the ipad 3 glass?
can the home button flex be torn taking the glass out or is it if your trying to remove the flex it's self.
I found what was causing my problem for me. the doc connector microphone goes in to a small black rubber housing. if the small hole of the mic and the rubber housing do not line up correctly the mic will not work. i removed the rubber housing and tested the phone and it worked perfectly. i had no blockages in the housing, just not in position properly.