A response elsewhere in this site suggested that a reason the home button may not work is that the damage causing a home...

My 4S keeps restarting every 4 - 5 minutes while charging, after installing a new battery. Once charged it works normally,...

Often the ribbon cable from the digitizer is not fully inserted into the mating connector. Ensure the dotted line on the ribbon cable is barely visible, and straight across or parallel with the edge of the mating connector.