always use samsung original charger which is provided with your smartphone box & don't use third party apps format your smartphone and make sure your phone software is updated to latest firmware.
To resolve auto restart issue please follow below given steps:- Go to Settings > General management > Reset > Turn off auto start.
If the issue still persist kindly visit the service center for the physical inspection of your device. To check for the nearest Samsung service center kindly click on the link:- https://www.samsung.com/in/support/service-center/
