I've searched for an answer already, but I may not be using the right terminology. Regardless, I wasn't able to find an answer.
I bought a mini PC with an eMMC HD and I'm trying to overwrite the existing OS (Windows 10) with a distribution of Linux from a USB drive. I changed the boot order to run all possible USB devices (there were five listed) before the HD, but it kept loading Windows. Eventually, I removed the HD from the boot order altogether and it's still booting to Windows. I'm not sure how this is possible, but it seems to be overriding my boot order preferences.
I read in a few places to disable Secure Boot. That's disabled. I also read that it should be installed in CSM mode, but that's not an option that I can see.
I don't know if this is worth mentioning, but it's the Aptio Setup Utility by American Megatrends.