After Beat, Bra, and Gast were helped by Robelu in escaping the destroyed Universe 0, they arrived in the returned Dark Demon Realm, and fought their way through hordes of Demon Realm Soldiers, before they came upon Towa's Lab, Where they found the unconscious Dark Broly, along with a Broken Time Breaker Mask that looked familiar to Beat. Upon getting a closer look at it, Beat remembered nightmares that he had of a masked figure with the same mask attacking the Time Patrol's base. As he pondered what that meant, he suddenly regained memories he didn't know he had. Upon seeing all that had happened, from the point of view of the attacker, he realized that it was him under the mask. The weight of realizing he had killed tons of Time Patrollers, mixed with the realization that he wasn't actually Towa's son, he wasn't even a member of her family, he was a pawn, caused something to snap inside of Beat, as he awakened the Super Saiyan God form.
Wait, so he obtained Super Saiyan Blue/Super Saiyan God through anger? Or was it grief?