Shut down the computer.
Enter BIOS setup (Power + Vol Down)
Enable BIOS password: Security > Supervisor Password
Don't forget this password. There is no easy way to reset it!
Erase secure boot settings: Security > Erase all Secure Boot Settings
Disable secure boot: Boot > Enable or Disable secure boot check
Change Boot Order to boot from USB first: Boot > Boot Priority Order
Enable boot menu (optional): Main > F12 Boot Menu
Save Changes: Exit > Exit Saving Changes