Reactivation Lock Help Needed - Can't Turn Off

I have an SM-G925A.

Purchased second hand from a seller I know.
Had his Samsung account on it and Reactivation Lock was turned on. We put phone on Wifi and tried to turn off Reactivation Lock. Just loops back to same screen and remains turned on.
Correct Password and Email as we were able to hard reset phone and at the Reactivation Lock screen during setup, it was accepted and we continued through to set up phone.
Still Reactivation Lock won't turn off, just loops back to same screen.
So we decided to delete Samsung account from phone.. Email and Password accepted, Samsung account deleted.
Thought we were good. Nope.
Now Reactivation Lock is on, grayed out and we cannot add back the Samsung account. Press on Add Samsung account and nothing happens.
Also cannot do Factory Reset from within Setting. Just press Reset Device and nothing happens.
Can't try flashing stock Rom as it's on AOF4 and no Rom to be found online.
There is no OEM Unlocking option in Delevoper Options either so can't try that.
I know I have seen other users with different S6 devices with similar problems after spending time searching on here.
Has anyone found a solution?