Multi boot system but no Grub Menu

[dragonfly41]

Just guesswork but since SSD was mentioned (HDD installation was o.k. I understand) does this separate thread raise any clue? Or a red herring?

https://ubuntuforums.org/showthread.php?t=2342662

I've read about Zorin now so at least I'm better informed.

[yancek]

GRUB_DEFAULT=0
GRUB_TIMEOUT_STYLE=menu
GRUB_TIMEOUT=10

Above is your output of the Ubuntu /etc/default/grub file which you posted in post 67. That is the default and should allow the user to see a menu on boot.

Found Zorin OS 17.1 (17) on /dev/sda2
Found Linux Mint 21.3 Virginia (21.3) on /dev/sda4

Above is the output when you ran sudo update-grub while booted into Ubuntu which was in post 30. That should put the Zorin and Mint entries in the Ubuntu grub.cfg menu. When you boot into Ubuntu, go to the /boot/grub/grub.cfg file and see if those entries (Zorin and Mint) exist in that file.

You have indicated several times that you have no "grub' menu but apparently see somethng on screen when booting to make a selection. Is that the case or have I not read correctly? If it is the case, could you use a smart phone or digital camera to take a photo of the screen and post it here. Or are you blindly hitting the down arrow key and then enter to see what happens?

[SUPERFITTER]

After wasting four hours reinstalling the three systems, I could not boot any of them.
I formatted all of them and tried one at a time to see if they would boot after installation.
I finally got Mint to work.
I updated it and rebooted and it works. I'm going to stick with one system for now.
I loaded rEFind Boot Manager from a different computer and installed it to a Thumb Drive that was formatted to Fat32 same results as previously posted.

Thank you for the help!

[1fallen]

Wise to stay with one OS.

If you want to play with more than one OS use KVM (Virt-manager) or Vbox it's much safer that way.