Reboot Sheriff CSM, and press Del or Delete to launch the BIOS Setup Utility.
Using the arrow keys, move to Boot.
On Boot Settings, move the cursor to Boot Device Priority and press Enter.
On Boot Device Priority, move the cursor to 1st Boot Device and select your USB device by using the + and – keys.
To exit, press Esc.
On Exit Options, move the cursor to Save Changes and Exit and press Enter.
Press Enter again to confirm.
Reboot Sheriff CSM.