When you said you held home and power button - did the phone go through a reboot cycle with the Apple logo?
Did you also close all background apps running and then reboot. I would double press the home button and swipe up all the applications open to close them all. Now turn off the phone completely by holding the power button until turn off switch comes up. Slide that and wait a minute. Then turn on with the power button until Apple logo seen. See if that works with all the apps closed.