My name is Ankit and I work for the Social Media and Community Team at Dell.
I understand that your system is not shutting down properly. It keeps on restarting on it's own.
Firstly, check if you are clicking on shut-down or restart from the startup menu.
Secondly, you can remove the ac adaptor & battery from the system & press down the power button for 1minute to remove the unwanted static energy.
You can also go into advanced boot options by tapping the F8 key at Dell logo.
In the advanced boot options, there is an option saying turn off automatic restart.
I hope this should resolve the issue.
For any further queries, feel free to reply back on the post.