Updating OS on rooted SMP600

Hi, so I have a Samsung galaxy note 10.1 2014 edition and quite a while ago, I rooted it on Android 4.3, so it's stuck there. I'd like to upgrade to at least 4.4.2, but because I tripped the Knox trigger (I think?) I can't updates even with attempting an unroot. I've spent hours searching for a solution, but the best option I can find is the to find the OS I want and try flashing it? Is this correct and if so is there a free program I can use to do it? (Odin's on play store)
If someone could PM me links for relevant files, that would be very much appreciated.
Thank you!!

How can I unbrick my SM-P600 Note 10.1 2014 ed.

My Note 10.1 2014 Edition is stuck on the tablet title screen, not sure if its in reboot mode it returns to this screen if I try to shut it off... basically Its frozen, and when I try to shut it off it goes away a few seconds and comes back. This happened after I rooted with KingRoot, and tried to Flash a ROM, Im a complete Noob and should have done my homework... but I didnt. I see everyone suggesting odin and going into download mode... I can get to download mode but I am using a macbook pro, and there are very little options to use odin, I tried Jodin3... and Heimdall... no luck...

PLEASE HELP !