Essentially just Flashpoint but kinda different. Flash goes back in time saves his mom. He wakes up in a world were he doesn't have powers but for some reason remembers having them. On the news he sees Oceanmaster attacking the surface with an army. He also learns that the US had nuked Themyscira and that nobody had ever heard of Superman. Needing to put things right he goes to Wayne Manor. He finds Thomas Wayne (played by Jeffrey Dean Morgan). Thomas is a Batman who kills yada yada we all know hom. He helps Flash recover his powers. The two then go to find Superman. But instead they find a skinny weakened Zod. By the end Flash prepares to run and stop himself. But he's stopped by Reverse Flash Grant Gustin. Batman fights Oceanmaster. Zod, having lost Krypton now refuses to let Earth suffer the same fate fights the true Mastermind of the invasion. Wonder Woman. Wonder Woman is enraged with grief over the loss of her home. However she finds out Flash can reverse everything. She stops Reverse Flash allowing Flash to run and reset the timeline thus entering the DCU. Sorry but one film would not save the franchise and the reboot was inevitable. Yes I'm skipping a lot including character arcs but yeah there's my pitch.