Turns out that my S3 had a faulty eMMC chip and had to have the chip and the motherboard replaced.
NOTE TO OWNERS OF 2012 MODEL I9300 GALAXY S3:
I did not know this before I had the problem but there is apparently an APP on the PLAY STORE called eMMC Brickbug App.
That will apparently check your eMMC status. Since I was not aware of this app beforehand I cannot say for sure if this app
does or does not work. However I previously owned and since gave away a 2013 late model Galaxy S3 which had no issues
whatsoever. From all the details that I have read, it seems that most 2012 models of the i9300 are more susceptible to this kind
of problem. If you own a 2012 model please take extra care when flashing any type of software, even if its original from Samsung!
Finally thanks to all the Posters who have attempted to help me out. I'm sure that all of your suggestions would have fixed the issue had my
phone not been hard bricked in the first place.