Hi, ponce; yes, i checked even before installing that Fast boot or secure boot was disabled, for cases like this, and no i cleaned my Hard Drive completely for Zorin or OS, and my BIOS is in UEFI - and i used an Pendrive about 4 gb in storage - which if thats the problem, please say for me - and steam i used the .deb version.
And, sure, i will try the boot repair