[Context: I am more than ready to end my ~35yr relationship with MS and, after many hrs investigation, have chosen Linux Mint Cinnamon 22 as my next main OS. In order to ensure I can still use some key previous apps & games, I have set up an old DELL laptop (Intel© Core™ i5-8350U CPU @ 1.70GHz × 4) as a dual-boot machine with a view to doing the same for my Acer desktop (Intel(R) Core(TM) i5-8400 CPU @ 2.80GHz) and newer Nitro V15 Laptop once I can demonstrate to my family that it works properly.]

Aim: I want to see the boot menu when I start the machine showing Linux Mint as the primary option and Windows 10 as the secondary option with a 10 second countdown.

Problem: Although both OS are installed (see image), and I can choose which OS it boots into automatically in the BIOS Setup (using F12), if I select Windows10 as the preferred OS, the boot menu only shows Windows 10 as an option (twice, now), and if I select Linux Mint as the preferred OS, it doesn't show the boot menu at all.

Things I've tried:

• bcdedit in windows
• Manually reinstalling grub by following the answer here: https://askubuntu.com/questions/683108/grub-menu-not-showing-at-boot
• opened command line in windows as admin and typed this command: bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi
• changing the FastBoot option to 'Thorough' (Note: this is REALLY BAD! It then refuses to boot into Windows 10 saying that the file has been tampered with forcing me to reinstall Windows!)

[Context: I am more than ready to end my ~35yr relationship with MS and, after many hrs investigation, have chosen Linux Mint Cinnamon 22 as my next main OS. In order to ensure I can still use some key previous apps & games, I have set up an old DELL laptop (Intel© Core™ i5-8350U CPU @ 1.70GHz × 4) as a dual-boot machine with a view to doing the same for my Acer desktop (Intel(R) Core(TM) i5-8400 CPU @ 2.80GHz) and newer Nitro V15 Laptop once I can demonstrate to my family that it works properly.]

Aim: I want to see the boot menu when I start the machine showing Linux Mint as the primary option and Windows 10 as the secondary option with a 10 second countdown.

Problem: Although both OS are installed (see image), and I can choose which OS it boots into automatically in the BIOS Setup (using F12), if I select Windows10 as the preferred OS, the boot menu only shows Windows 10 as an option (twice, now), and if I select Linux Mint as the preferred OS, it doesn't show the boot menu at all.

Things I've tried:

• bcdedit in windows
• Manually reinstalling grub by following the answer here: https://askubuntu.com/questions/683108/grub-menu-not-showing-at-boot
• opened command line in windows as admin and typed this command: bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi
• changing the FastBoot option to 'Thorough' (Note: this is REALLY BAD! It then refuses to boot into Windows 10 saying that the file has been tampered with forcing me to reinstall Windows!)