Are you sure kb is working? try the USB 2 slots at back, Del is key you should be using to enter bios
In your bios, HIt F7 to go into advanced mode, and on the settings/boot menu there should be a setting for both MSI fast boot and fast boot, you may need to disable both for the USB to be bootable. See page 46 & 47 of your manual.
You may also want to look at Secure boot as well, on page 47.