Lately these past few days, my phone has been restarting and I have no idea why. I don't have my auto restart on just in case you were wondering. It only happens when I have an alarm or a timer set. It'll make this REALLY LOUD noise and then automatically restart. If anyone has a solution, I'd greatly appreciate it.
Let's try wiping the system cache partition on your device to see if that helps any.
- Turn off the device.
- Press and hold the Volume Up key and the Bixby key, then press and hold the Power key.
- When the Android logo displays, release all three keys.
- An 'Installing system update' message will show for 30 - 60 seconds before the Android system recovery menu options appear.
- Press the Volume down key several times to highlight wipe cache partition.
- Press the Power key to select.
- Press the Volume down key to highlight yes, them and press the Power key to select.
- When the wipe cache partition is complete, Reboot system now is highlighted.
- Press the Power key to restart the device.
I would also recommend booting your device in safe mode to see if a third-party may be causing this to happen.
This step will temporarily disable all your third-party apps, but none of your personal data will be deleted. Your customization settings (Wallpaper, Themes, et cetera) will be reset to default once you exit this mode.
Please follow the steps below:
1. Turn the device off.
2. Press and hold the Power key past the model name screen.
3. When "SAMSUNG" appears on the screen, release the Power key.
4. Immediately after releasing the Power key, press and hold the Volume down key.
5. Continue to hold the Volume down key until the device finishes restarting.
6. Safe mode will display in the bottom left corner of the screen.
7. Release the Volume down key when you see Safe Mode.
8. To exit Safe Mode, restart your device.
Let us know how your device responds after performing this step!