Make sure that the latest version of iOS or iPadOS is installed on your device, and make sure that your application is the latest version. If the problem persists after updating the software and applications, please check your hardware.
Check your hardware.
For iPhone 6 or later, in battery health, click settings > battery > check the battery health.
If your battery does not need maintenance, but your iPhone, iPad or iPod touch is still frequently restarted or turned off, please contact Apple Support.
If your App exits unexpectedly, please know what to do.
Know what to do if the screen of an iPhone, iPad or iPod touch device crashes, doesn't respond or gets stuck when it is turned on.
Learn more about what to do when your iPhone, iPad or iPod touch unexpectedly restarts or shuts down, displays the Apple logo or turns gears.
For additional assistance, please contact Apple Support.