Dual boot install zorin on Windows 10

Hello,

I'm trying to help someone over the phone, so I don't have all the information. They called me and told me they have been trying to install Zorin Core.

they have Zorin CORE on a USB drive and are trying to install it on their
9-year old MSI desktop computer.

they have windows 10 on a physical C:\ drive.
they have data on the physical D:\ and E:\ drives
and a physical HDD F:\ drive where they want to install Zorin Core.
( it sounds like each drive has several partitions )

he said the Zorin installer with UEFI ( /u ) option works and installs all the way to a Zorin Desktop. He said he can surf the internet, so it sounds like it is fully installed.

He reboots the computer but does NOT get any boot options or boot-loader and the computer just boots into Windows 10.

He has done the Zorin installer 8+ times and it always seems to work with the UEFI installer options.
he said he also tried it with the "No UEFI" and that install fails with an error about Grub was not able to be installed

He said when he goes into Windows 10, He can see partitions on the F:\ drive that appear to be Zorin,

so, it sounds like he is installing it but the GRUB bootloader is not setup, because after a reboot, the computer will not show a boot-loader and will only boot into windows 10

Are there any tips you can give me to help him?

Thank you

Phill.

Well, an hour late to the phone call but...

Some Manufacturers are now locking down the EFI settings to Only Allow Windows OS to boot.
It's a thing.

So, things you can try: Disable secure boot - then test.

If no good, enable Secure boot and try this option:

Welcome to the Forum!

Does the Friend have checked the BIOs if Secure Boot and Fast Boot are disabled? And is Fast Start-Up in Windows disabled? Can the Friend see in BIOS an ''ubuntu'' Entry in the Boot Order?