Well, I went ahead and set the bootable order anyway (with this ubuntu thingy being the 1st, then DVD the second, and lastly the HDD), then restarted the computer but when it got to booting from the USB device (which again, the UEFI detected as 'ubuntu (Drive not present)' device) it simply skipped it, skipped the DVD option, too (because I had no bootable DVD inserted), and proceeded to boot from the HDD. I just created a bootable USB with Linux Mint 19 Xfce, then went into BIOS (well, UEFI actually cause that's what it's called on my computer), and when setting the booting order I have noticed that the USB drive is detected as 'ubuntu (Drive not persent)' (yep, these are the exact words of my bootable USB drive). I'm having a problem with my bootable USB drive not being recognized by UEFI.
