Well, that’s not the point anyway. We’re trying to fix an issue here so here are the ways, in which you can try to fix your iPhone that keeps shutting off, restarting or freezing.
Turn ON/OFF Cellular: As strange and absolutely impossible as it sounds, I’ve seen people get this issue sorted out by turning off their cellular data and then turning it on again. Arguably, this doesn’t work everywhere. But since this is the most simplest thing you can try, you should begin here. Don’t believe me? To do so go to settings → Cellular/Mobile → Turn On/Off Mobile Data.
Reboot iPhone: To reboot your iPhone, hold the power button and home button simultaneously for a few seconds. The Apple logo will appear on the screen and your iPhone is rebooted.
Reset iPhone: To reset your iPhone, go to Settings → General → Reset → Reset All Settings.
Faulty App: No matter how strong and protected the App Store is said to be, there are apps that aren’t really good for the health of your iPhone. One of these, possibly, could be ruining your iPhone experience. Did you download any new app that triggered the issue? It doesn’t matter if it’s a popular app or an app that no one has ever heard of. Just try deleting it.
Delete the app → Reboot your iPhone → Sync with iTunes and see if this sorts the issue.
Restore From An Old Backup: No luck yet? Try this method (it’s tougher if you’ve got an iPhone that keeps restarting too often). Connect your iPhone to iTunes on the system and then restore from an old backup. In case you got lucky, things will be back to normal.
Recovery Mode + Restore: This could be the best possible solution you could ask for. Again, it’s tougher to implement if your iPhone keeps shutting off or rebooting every two-three minutes.
Hope it can help you https://support.apple.com/en-us/HT203899