You have to use 1040X.

1045 can only be used within 12 months after the year end of the NOLY year. i.e 2018 NOL, 1045 had to be filed by 12/31/19. There was some extension when they passed the 5 year carryback period but that is no longer available.

SE tax cannot be eliminated by an NOL carryback. Either you input something wrong or the amendment generated some credits that wipe out the total tax liability.