Hi guys and gals, I am trying to create a bootable USB with a custom linux distro on it, it is one used to upgrae my SSD firmware. Unfortunately, I took out my ODD to put in an Optibay HDD dock, and as such am unable to use a CD. I am using tools which have worked in the past, but for some reason, my MBP is not picking it up as a bootable USB. I have tried multiple keys, none of them work, and the External DVD drive I am using doesn't seem to want to boot into anything either... even Windows discs won't boot. Any advice?