i am using iphone 6s - space gray -64g --ios 9.3.3 it was working good until 2days ago. when i pick my phone from the pocket for watching time, i press the power button but nothing happened. so i pressed home button either but nothing happend too. the screen was black and i thought it was frozed up!!! so i pressed home button + power button together for force rebooting..... i pressed about 6 seconds but it didn't work so about 2 minute later i did force reboot about 5seconds then it was turned on ㅠㅠ since that trouble shooting it works fine right now. but i don't have much referbish time(remaining warranty time) so, i went to the service center, then they said ' if there was mainboard problem, there will be log about trouble shooting' but, i don't think this is true!!! does anybody has this problem???? and do you know why this symptom happen?? is this hardware problem or software problem??? plzplz help me thanks !!