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.
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 assume also from because they dont comment on the glass that it is the same as the ipad 3 glass?
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.