Using Rufus (https://rufus.ie/) to create an EFI friendly USB Linux boot setup was the key I needed to get Linux running on my Cosmos VII. In Rufus, Choose partition type GPT and the target system is auto set to EFI. From then on it was a trouble free and instantly working installation. Dual boot with Windows 10 (yuch).
I had tried Ubuntu and created a USB boot installation using another creator (UNetboootin, I think) and had spent a long time trying on different occasions to get it running, to no avail. I had decided not to get a DVD drive with my machine.
I had already turned off Windows 10 fast boot, and also turned off secure boot.
I am very much liking Peppermint, so far!
I had tried Ubuntu and created a USB boot installation using another creator (UNetboootin, I think) and had spent a long time trying on different occasions to get it running, to no avail. I had decided not to get a DVD drive with my machine.
I had already turned off Windows 10 fast boot, and also turned off secure boot.
I am very much liking Peppermint, so far!