Safe Mode puts your phone in a diagnostic state (returned to default settings) so you can determine if a third-party app is causing your device to freeze, reset or run slow.
Ensure the device is powered off.
Press and hold the Power button (located on the top edge) to power on the device.
Hold the Power button until the Samsung logo appears onscreen then release.
With the Samsung logo onscreen, press and hold the Volume Down button (located next to the Power button).
When the device displays Safe Mode in the lower left, release the Volume Down button.
With Safe Mode enabled, test device and app functionality. If the previous issue fails to occur, the cause has been isolated to a third-party app and all recently installed or updated apps should be uninstalled.
Power cycle device to disable Safe Mode then reinstall and test each app one at a time to identify which app is causing the problem.