Lollipop update?

Hey all,
I recently unrooted and have my Knox at 0x0 (as out of the box as possible).
I tried to update to lollipop and the update keeps failing.
I know this is common, but I'm having trouble finding a solid answer as to what to do about it.
I swear I looked for answers, but I keep finding updating a rooted phone. Thoughts? Did I not unroot completely?

Thanks in advance.