what motherboard do you have? what brand M.2 drive is it?
I think there are extra steps needed to install onto M.2 drives. I don know you won't want the hdd attached when you do it. ONce you tell me the answers to top two questions, I will see what I can find
How to clean install win 10: http://www.tenforums.com/tutorials/1950-windows-10-clean-install.html