the System will not boot without Installer USB. For that you need Ubuntu/Linux USB Installation. To make it boot without Installer USB, you have to follow these steps. (I spent 1 day to fix that, but RehabMan helped me a lot, and thats why i bought a Sticker with TonyMacx86 logo (its on my MSI now) + one Coffee Mug :).)
In Ubuntu/Linux terminal:
RehabMan guide:
"
# add Clover entry
sudo efibootmgr -c -L "Clover UEFI" -l "\EFI\CLOVER\CLOVERX64.EFI"
Most of the time, the new entry will be added to the BootOrder first.