I need to get to work quickly with several apps pureOS doesn’t yet/easily support. Am trying to get Ubuntu 17.10 running on my Librem13 but cannot boot from the Hard Disk (USB live boot) at the boot menu. Can anyone assist me in replacing PureOS with Ubuntu?
Did you succeed? What are the symptoms you observe (“cannot boot” = ?)?
AFAIK there is a boot menu when you press ESC after switching the computer on but the USB stick or HDD drive must be prepared to contain the required boot files by transfering the Ubuntu ISO file with a tool (not just copying the ISO file on the drive…