first of all, sorry for my english, well, I have tried to install elementary OS as a dual boot a loooot of times(I got Windows 10 installed) those days. Always the same problem:
grub-install/dev/sda failed. Fatal error!
My computer doesn't have options for secure or fast boot (Lenovo z475). I've tried installing from USB flash made with Etcher, Rufus, even through a burning DVD with the .iso and nothing... Is there some steps by steps instructions to solve this problem (I'm just a beginner)?If someone could help me, I would appreciate a lot!. If don't, it's ok (y)I'll understand , thanks in advance!...(Y) (Y)