Ubuntu, UEFI and hard disks

[Linux for blind general discussion]

I posted this over at askubuntu but I figured I'd ask here too. Got my 
laptop to boot into Ubuntu Mate. Problem is...it won't detect the hard 
drive at all. I can do slblk and all it shows is dev/sda (which is the 
USB stick). Installer picks up the stick too and tell me I need 8GB of 
space on the 8GB memory stick.

I went into Win10's settings and turned off UEFI, then secure boot. So. 
Should I reenable the UEFI firmware but leave secure boot off, or...?