Launch a new instance (recovery instance).
Stop the original instance (DO NOT TERMINATE)
Detach the volume (problem volume) from the original instance
Attached it to the recovery instance as /dev/sdf.
Login to the recovery instance via ssh/putty
Run sudo lsblk to display attached volumes and confirm the name of the problem volume. It usually begins with /dev/xvdf. Mine is /dev/xvdf1
Mount problem volume.
$ sudo mount /dev/xvdf1 /mnt $ cd /mnt/etc/ufw
Open ufw configuration file
$ sudo vim ufw.conf
Press i to edit the file.
Change ENABLED=yes to ENABLED=no
Type Ctrl-C and type :wq to save the file.
Display content of ufw conf file using the command below and ensure that ENABLED=yes has been changed to ENABLED=no
$ sudo cat ufw.conf
$ cd ~ $ sudo umount /mnt
Detach problem volume from recovery instance and re-attach it to the original instance as /dev/sda1.
Start the original instance and you should be able to log back in