The S9700 will turn itself off to save the battery, when it sits inactive for a period of time. Also check the battery, the S9700 will turn itself off if the battery is dead.
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Try taking a look at this page for more information: https://www.ifixit.com/Wiki/Nikon_CoolPix_S9700_Troubleshooting#Section_S9700_Turned_Off_Without_Pressing_the_On_Off_Button
The S9700 will turn itself off to save the battery, when it sits inactive for a period of time. Also check the battery, the S9700 will turn itself off if the battery is dead.