Yes, that should help you.
In addition, for Grub Menu, check your grub file:
sudo nano /etc/default/grub
At the very bottom, your Grub theme should appear as:
GRUB_THEME=/usr/share/grub/themes/zorin/theme.txt
Ensure it is present -or re-add it if needed. Ensure it is not commented with a # symbol at the front of it.
Once you have made any needed changes, do be sure to run sudo update-grub again...
EDIT:
In addition, please see this post:
for another tip on checking /var/log/ for installed or upgraded packages through dpkg.
This may be helpful for finding any other remaining changes that could haunt you later - such as a package that you wouldn't remove having been upgraded according to Pop_OS repos, but not to Zorin OS Repos. That could causes you mysterious headaches later after this event has faded in memory.