There are several potential reasons why a Samsung phone may keep restarting or rebooting unexpectedly. Some common causes of this issue include:

1. Software problems: A phone may restart or reboot due to software issues, such as a bug in the operating system or a problem with an app. These issues can often be fixed by updating the operating system or uninstalling and reinstalling problematic apps.
2. Hardware problems: A phone may restart or reboot due to hardware issues, such as a faulty battery, damaged charging port, or a hardware component that has failed. These issues may require repair or replacement by a professional.
3. Overheating: A phone may restart or reboot due to overheating, which can be caused by extended use, exposure to high temperatures, or running resource-intensive apps or games. Allowing the phone to cool down and avoiding prolonged use or exposure to high temperatures can help prevent overheating.
4. Malware: A phone may restart or reboot due to malware, such as a virus or malicious app. Installing antivirus software and avoiding downloading suspicious apps or opening unknown links can help prevent malware infection.
5. Factory reset: If a phone is experiencing persistent problems that cannot be resolved through other means, a factory reset may be necessary. A factory reset will erase all data and restore the phone to its original factory settings, but it should be used as a last resort as it will delete all personal data and installed apps.

In conclusion, there are several potential reasons why a Samsung phone may keep restarting or rebooting, including software problems, hardware problems, overheating, malware, and the need for a factory reset. Identifying the cause of the issue and taking appropriate action, such as updating the operating system, uninstalling problematic apps, or seeking professional repair, can help resolve the problem and prevent further issues.