Hi, I updated my elive system using bash command elive-upgrader -upgrade in terminal. It upgraded my elive operating system. This computer is a multi-boot with windows 10 and another Linux system besides Elive installed. I have grub2 loaded on the computer and used it to boot the system of choice at boot time. After the Elivecd upgrade as described, grub2 no longer appears at boot and the other two systems besides Elive don't appear on the Elive boot menu.
How do I fix this to get booting from Grub2 back, and have access to the other two operating systems?
That would suggest that Grub2 did run. If you can boot into Elive you could try and re-configure grub2 from there with 'sudo grub-install'.
The routine should tell what is being seen and used.
I did as you suggested, see below:
#sudo grub-install 127
Installing for i386-pc platform.
grub-install: error: install device isn't specified.
#grub -install
zsh: correct grub to ruby [nyae]? n
zsh: command not found: grub
#grub -install
zsh: correct grub to ruby [nyae]? n
zsh: command not found: grub
I searched for grub2 using Synaptic Package manager and it says it's installed. I reinstalled it and will post the results shortly once I reboot.
No change on reboot after reinstalling Grub2 using Symantech Package Manager, the other operating systems still aren't recognized.
There are 2 things that catch my eye.
1.) There's a trailing "127" in your command, which shouldn't be there.
- What is the output of "dpkg -l |grep -i grub2"on your machine?
If it is not marked as deb13 you should replace it with the new version.
- If it is the new version, then re-install with "apui grub-efi-amd64" or "sudo dpkg-reconfigure grub-efi-amd64"
2.) You mention Symantech Package Manager ..... never heard of it but I'm guessing it's a typo for synaptic. 
Anyway, another option is to download a "super grub2 boot disk" .... boot from it and see what it recognizes as bootable OS's on your machine.
Make sure your /etc/default/grub file has the setting GRUB_DISABLE_OS_PROBER uncommented and set to "false", sometimes seems to be overwritten on upgrades and that makes other OSes not show
then run again:
sudo update-grub