Welcome to the Dell Community @mhmt 

Try this.

Go to "Settings"

Then to "System"

Then on the left hand side click on "Power & Sleep"

Then on the right hand side click on "Additional Power Settings"

Then on the left hand side click on "Choose what Power Buttons Do"

Then click on "Change settings that are currently available"

Then un-check "Turn on fast startup" then "Save Changes" and reboot.

Best regards,

U2

Greetings, 

Hope the below steps have helped you to resolve your query. Do write to us here for further assistance or any other query. We're happy to assist you 24/7. 

-Pratheepan.