Edited grub - cant boot LL

[thoughtinstinct]

It doesn't open grub file for some reason.

Code:

linux@linux:~$ sudo mount /dev/sda5 /mnt
mount: /dev/sda5 is already mounted or /mnt busy
       /dev/sda5 is already mounted on /mnt
linux@linux:~$ for i in /dev /dev/pts /proc /sys; do sudo mount -B $i /mnt$i; done
linux@linux:~$ sudo chroot /mnt
root@linux:/# leafpad /etc/default/grub
No protocol specified
leafpad: Cannot open display:
root@linux:/#