Secure boot is probably to blame, but I have no idea how to turn it off without a good BIOS. Flashing the BIOS should help, but you need access to F12 to do this from a USB stick.
I was having fan issues and loaded the defaults for the bios.  Now, when it boots it stops at this message: "Alert! Hard Drive not found. To Continue press F1 Key"  etc etc etc I am booting into Unraid from an internal USB drive.  Once I press F1 it continues fine and boots into the USB Unraid OS. I cannot find in the bios or elsewhere how to disable that message so it can boot without keyboard intervention.  Any ideas?  It wasn't doing this before. Also, my boot order in the bios only lists the USB Drive, nothing else.  Thanks,  
Remove 'Hard Drive not Found.' warning message and continue booting