What changes with e(edit)?
Maybe you can open the Terminal in Manjaro again.
sudo nano /etc/default/grub
You can also remove quiet splash there (to get rid of plymouth).
Do your changes again what you did earlier after pressing E, save the file and then:
sudo grub-mkconfig -o /boot/grub/grub.cfg
How you did remove 6.9 any logs? Did you do that with manjaro settings manager?
@neogeo
There is also the option to use install-grub Script that may could automatical repair your broken grub, with reinstalling (included newest Grub version) the whole grub instead just repair/update, check this article out if you want:
In short download install-grub and then:
sudo pacman -S grub
Should be enough.
Restart and when you look inside your Grub Menue a new version should show up 2.12-4 that you have the latest Grub Version.