Were you ever disappointed the New 52 never really followed up on Flashpoint? Me too! Now six or seven years later, we're finally vindicated!
The Spoilers:Reverse Flash is dead and Batman is bedridden with some serious injuries from his fight, now it's up to The Flash to figure out just what happened. Even when Bruce is barely able to move, he talks detective with Barry, trying to figure out the link between Reverse Flash, the button, and the death. Neither come up on anything solid to move forward on, but Barry holds back a bit, thinking what he needs to do may be too dangerous for anyone else.
Barry detected the same radiation that the button gave off on Reverse Flash's corpse, and lots of it, so despite his swearing never to do so, he breaks out the Cosmic Treadmill in the Justice League vault (which is FULL of continuity shit you wouldn't see in the New 52) to track down the source of the radiation.
Unfortunately for Barry, Bruce detected the vault being open and insists he comes too. Barry tries, but can't convince Bruce to stay home, and off they go. The speed force is a mess and what Barry describes as a "storm" is headed right for them. Before they can leave, they see visions of the past that don't make sense to them, such as the Justice League forming (like, Silver Age… or Gold Age… Bronze? I can't keep those straight) or Identity Crisis, with Zatanna and her terrible head gear wiping Batman's memory. They initially think that these could be alternate realities, but then think that these visions could be from the stolen time Wally West had mentioned.
The two eventually crash in what looks to be a very meager Batcave, which Bruce recognizes instantly, though something's off. All comes apparent when Bruce is met with his father, in full Flashpoint Batman get up.