I changed the battery on my 5s and the first thing I noticed was the power and sound buttons became unresponsive. These buttons are connected via push type (lego style) connectors to main board. Not knowing which of the four or five connectors was not properly in place, I disconnects them all and carefully pushed them back in till heard snap sound and/ it was comfortable that they are in. That's it. Resolved the unresponsive power and sound buttons problem.