operation system not found after fresh install

I have an old Dell laptop I bought back in 2011 which I wasn't using (I'm now using a newer laptop.)
It has and I7 CPU, with 8 GB of memory and two 750 GB drives. It's an XPS Dell.
I wanted to try Linux so I downloaded Ubuntu and installed it on the old laptop. I chose the option to delete everything on the hard drive. After the installation the error message: "operation system not found" came up. I tried reinstalling (also with option to delete contents of hard drive so I wouldn't have two installations of Ubuntu.) Same result.
I then downloaded "Mint" and installed it with the same result. (I also chose erase the drive during this install so I wouldn't have two different versions of Linux.)

I've tried numerous "fixes" but none worked.

I tried these:
set prefix=(hd0,msdos1)/boot/grub
set root=(hd0,msdos1)
insmod normal

insmod linux
linux /vmlinuz root=/hd0/msdos1
initrd /initrd.img
boot

Never got past the "vmlinuz" because it couldn't find it.

I'd appreciate any help getting this booted. I'd love to dump Windows!