Did you tap F9 at boot? If you did this then you can download the iso version and use Rufus to create the bootable USB flash drive. I never had a problem with a USB created with Rufus. When you start Rufus select GPT partition scheme. Leave all boxes as checked. Where you see FreeDos select iso image and click the icon. Browse to the iso file you downloaded.
I would also make sure that SecureBoot is disabled in UEFI. Also if there is a Quickboot or Fastboot setting disable it. You flash drive should be detected in UEFI with it attached.
I can't say it is the same for you but in my BIOS there is a setting in the Boot section you need to highlight and press Enter in order to get to your USB removable settings. See this page on disabling SecureBoot.
Also see this.