He saw himself stopping his past self from saving Nora.
Focuses on the first time the heroes (Batman, Green Lantern, Superman, etc.) meet to stop an invasion by Darkseid. justice league flashpoint paradox part 2
Here is a deep dive into why there isn't a direct "Part 2," what actually happens next in the story, and the spiritual successor that finally closed the loop. Why There Is No Official "Part 2" He saw himself stopping his past self from saving Nora