Question: asus how to boot from usb?
Answer: Plug in your USB drive.
Turn the Zenbook on.
Enter UEFI (BIOS) through pressing ESC or F2.
In 'Boot' tab: 'Disable Fastboot' (*)
Press F10 to save & exit.
Immediately press ESC or F2 again.
In 'Boot' tab: your USB drive should be listed - change the order.
Press F10 to save & exit.