[kubuntu] Caot Boot Ubuntu After Partial Upgrade

Good day,

I am kinda newbie to Linux and today I have an issue with my Kubuntu system. I does not load into Linux anymore. I stops with some Busybox error.

My Setup:
Laptop with windows 8.1 installed.
I installed my ubuntu into EXTERNAL USB HDD. The grub too was installed in this Exteal USB HDD.
Usual Boot: I need to plug in the EXTERNAL USB HDD to boot to Linux. The grub will be shown and I can select my preferred OS to boot into. Without this exteal USB HDD, it will boot directly into Windows.

What Happened Today:
As usual, there was some updates available. I proceed to update. For some reason, the update failed and stopped.

Symptoms
I did not realize anything abnormal when the update failed, except my Thunderbird stopped working

After Reboot:
The system showed the GRUB screen. As per normal i selected UBUNTU to boot into and it failed with some busybox error.
I can still load into Windows but not Linux.

What I Did:
I tried repairing with Ubuntu Boot Repair, It claimed it repaired but still I am not able to boot into Linux.
I tried to load into fail safe and it too failed to load. Picking the previous keel too was no help.

PasteBin
paste.ubuntu.com/15407483

Any help and suggestion is much appreciated. Thank you.