The top answer to the question you linked to explains how to get into the GRUB menu if pressing shift does not work. You just edit the file
/etc/default/grub and comment out
GRUB_HIDDEN_TIMEOUT=[some number]. Then you run
Since you can't boot at all, you can't do that so easily.
However, you can do it from a live system, so go ahead and boot from a live system as you did before.
Now you can set up a
chroot. If you're not sure of the device label of your installation's root partition, try running
sudo fdisk -l to identify it. You should see something in the output like
/dev/sda2 <numbers indicating size> Linux filesystem
Try mounting that partition:
sudo mount /dev/sdXY /mnt
sdXY is the correct label. Then have a look to see if the mounted partition has the directories you expect to see in your root partition:
If you see things like this (not necessarily exactly like this, but at least most of them)
bin dev mnt root sys var
boot etc lost+found opt run srv tmp
home lib media proc sbin usr
then you got the right partition.
If you have a separate boot partition, you will need to mount it. If you are not sure, check the file
/mnt/etc/fstab to see if it has a partition mounted on
/boot. Ignore any mention of a partition mounted on
If you have a separate boot partition, mount it:
sudo mount /dev/sdXY /mnt/boot
sdXY is the correct label of the boot partition.
We might need to bind some additional resources (I am not sure this is necessary in this case):
for d in dev sys run proc; do sudo mount --bind /$d /mnt/$d; done
OK, now enter the chroot
sudo chroot /mnt
Now we can act as if we are in our installed system. First let's edit the configuration file:
(or call your favourite text editor). Find the line
(it may have a different number, but that is not important). Comment out the line by placing
# at the start of it, so it says
If you do not have the above line, look for
and comment that out instead to
check that the line
ends in a number greater than 0 (the default may be 10). Save the file and exit.
Run this command to write the configuration to
Now you can reboot into your installation, and the GRUB menu will be forced to come up every time.