cd /

cd <mount location>

cat etc/default/grub
sudo sed -i "s|splash|splash modprobe.blacklist=nouveau|g" etc/default/grub
cat etc/default/grub

sudo update-grub

sudo mount --bind /dev <mount location>/dev
sudo mount --bind /sys <mount location>/sys
sudo mount --bind /proc <mount location>/proc

cat mnt/etc/fstab

sudo mount /dev/sdaX <mount location>/boot

sudo chroot <mount location>
sudo update-grub
exit

Finally, reboot.

GRUB_DEFAULT=0
GRUB_TIMEOUT=1
GRUB_TIMEOUT_STYLE='hidden'
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash modprobe.blacklist=nouveau"
GRUB_CMDLINE_LINUX=""