Dual boot - why didn't it work?

Windows 10 Home (Legacy / BIOS) installed to begin with, I downloaded MX Linux and created an USB with balenaEtcher.

I followed a tutorial and did the following:

- Created two partitions, one for ESP and one for root.

- Installed by following the prompts, checked to create a swap file.

- GRUB install: ESP.

Everything installed but GRUB didn't boot, no boot option in BIOS related to MX. Checked the ESP partition and it did have the files, grubx64.efi etc.

I gave up and created a new USB with Rufus, that's what I did initially but I got some warnings about mismatches (different versions) about GRUB and syslinux, that's why I reverted to balenaEtcher. I clicked through the warnings and opted to download files, USB was created without error. I also chose MBR, since my system isn't UEFI.

- I did the same and created the same two partitions.

- Installed as before, but this time when I came to GRUB the option to choose ESP was greyed out, I had to go with MBR.

- Did not create a swap file.

Everything installed and it just worked, got the boot menu, Windows was there by default.

Everything is installed on the same SSD.

I'm curious to why it worked the second time and not the first?

Edited by Flintheart, 17 March 2024 - 07:08 PM.

Thank you for the answer.

I still don't have a entry in the BIOS relating to MX Linux, but it works so I guess it's ok.

The partition I made for ESP and marked as ESP during installation is empty. Before it had the GRUB files, is GRUB installed to the root partition when choosing MBR?

I don't dual-boot...never have.  I fined it much easier to have a windoze VM. 

I have a win 7 VM on my Mint Cinnamon system...it's not connected to the net and works just fine and can't kill Grub either.