ReadyNAS NV+ V2 Firmware Update: Stuck "Installing Addon"

Earlier this week I noticed that the Admin page for my ReadyNAS was no longer working (trying to open it in a browser give me a "site cannot be reached" error). I tried to start it manually using the following command via SSH:

root :~# killall apache-ssl
root:~#/usr/sbin/apache-ssl -f /etc/frontview/apache/httpd.conf

but got the following error: 

Invalid command 'ExtendedStatus', perhaps misspelled or defined by a module not included in the server configuration. 

Sometime ago I had manually updated my SABNZBD addon to the latest version and also tried to update the unrar package from version 4.x to version 5.x but to no avail. Not sure if this is related...

In any case, I figured I would manually update the firmware from version 5.3.11 to 5.3.12, and did so by running the following commands from SSH:

$ cd /tmp
$ mv /$downloadDir/RAIDiator-5.3.12 .
$ echo /tmp/RAIDiator-5.3.12 > /.cf_update_in_progress
$ reboot

On startup the ReadyNAS LCD screen showed "checking quotas" for sometime and is now stuck on "Installing addon" for several hours.

Any suggestions on what I can do to fix this?