Tootfinder

ALSO; even tho Gparted detected a RAID, the BIOS doesn’t seem to support RAID in the sata options: just ATA and AHCI

I’m installing #Linux for someone.
When I (try to) boot it, the computer (old dell laptop) says “Operation System Not Found”.
However, GRUB is installed: if I add in a #openSUSE USB and select “boot from hard disk” the installed grub opens and I can boot the system normally!! I need the pendrive only to select “boot from hard drive” - then it opens the installed grub and I can just remove the pendrive and boot.
It only isn’t opening Grub automatically apparently? Tho the BIOS doesn’t let me select a specific partition, only “hard drive”.
Legacy BIOS, MBR.
It’s a Dell XPS L511Z
Any ideas?
Relevant: Fedora installer wasn’t detecting any disks. So we installed openSUSE dual boot with windows (it worked, the only problem was grub didn’t detect windows). They wanted to try deleting the disk to see if fedora would detect it. Opening Gparted, apparently it was a RAID (even tho only 1 disk). Someone else deleted the disk (new partition table).
From then on, any distro we installed had the problem I mentioned.