1. Take out the SIM card and SD card at the same time, and then try to boot.
2. Please press and hold the menu key (left touch sensitive key) or the volume down key for a long time until the words "Safe Mode" appear in the lower left corner of the screen when you see the "Samsung Logo" icon, then release it and back up data (such as contacts, text messages, photos, etc. ) and restore the factory settings.
3. If you can't enter the safe mode or the problem still exists after operation, it is recommended to take the three-guarantee certificate of the mobile phone to the nearest Samsung service center for inspection and maintenance.