If I remember correctly, in all of the downfall games, after A link to the past, Ganon is resurrected (or at least there is an attempt), meaning that the guy is dead. It's more like summoning a spirit, or creating the un-dead, as apposed to breaking a seal. We need to look at the other two timelines to see what happens when Ganon's seal is broken.
The history of Ganon in the franchise is:
AT:
OoT-Ganon is born to the Gerudo. He breaks into the SR, takes the ToP, and rules Hyrule for seven years. He's defeated by the Hero of Time and the Awakened Sages seal him along with the ToP in the Dark World.
TWWBS: Ganon breaks free from his imprisonment, and due to the fact that the Spirit of the Hero no longer exists in the AT, Hyrule is unable to oppose him, leading to the flooding of Hyrule by the goddesses to seal him.
TWW: The seal of the gods fail, and Ganon is able to escape to the Great Sea through a portal in his tower. He becomes the master of the abandoned Forsaken Fortress, and starts deploying the Helmaroc King to kidnap pointy eared girls and bring them to him. At the end, he is completely eradicated due to Daphnes wishing for his demise, with the Hero of Winds fulfilling the wish.
CT:
OoT-Ganon is born to the Gerudo. The Hero of Time uses his knowledge of Ganon's actions to warn the Royal Family. Ganon is captured and sentenced to death.
TPBS: Ganon's execution fails, and he is sealed in the Twilight Realm instead of being killed.
TP: Ganon returns to Hyrule through Zant. He tries to blot out the light forever, but is killed by the Hero Chosen by the Gods.
FSA: New Ganon(only game in the series to have a different Ganon; even BotW Ganon is described as the same man who did battle with Ruto and Nabooru). He is the Guardian(not a king or leader) of the Desert, but is hated by his tribe due to him flouting the law. He becomes the Demon King of Darkness, and is sealed in the FS.
DT:
OoT-Ganon is born to the Gerudo. He breaks into the SR, takes the ToP, and rules Hyrule for seven years. The Hero of Time is bested by him in combat, and he receives the ToW and ToC. The Awakened Sages seal Ganon and the complete Triforce in the Dark World.
ALttPBS: The seal on the DW starts to weaken, and Ganon's malice and demonic army start to leak out. The Knights of Hyrule protect the Seven Wise Men while they cast their seal on the DW, keeping Ganon and his remaining demons sealed.
ALttP: Ganon splits his soul so he can exist in the Light World, and assumes the guise of the priest, Agahnim. He sacrifices the descendants of the Wise Men to break his own seal so he can fully return to Hyrule, but is killed by Link before he can leave.
Oracles: Is revived as an insane, primal beast, and is almost immediately killed again.
ALBWBS: Is revived, obtains the Triforce of Power again, and is defeated and sealed away ''in darkness'' thanks to the hero and sages of this period.
ALBW: Yuga releases Ganon from his seal. He dies again.
Zelda 1: Ganon is revived again, takes the Triforce of Power again, and is killed again.
BotWBS*: Ganon is eventually revived so many times that this fact along with his hatred for the hero and Royal Family makes him become Calamity Ganon, allowing him to completely separate his soul from his body, allowing him to lay waste to Hyrule without a physical body.
BotW*: Ganon returns, and is ultimately defeated and sent back to his body(like Agahnim in ALttP, and as we see in the BotW2 trailers).
*Most likely on the DT, hence why I included it there.
As we can see, whenever Ganon is sealed, there's an explanation for his his seal breaking, but that isn't the case always when talking about his deaths. We know he CAN be ressurected(that was established as early as Zelda 2), and It's explained how he comes back in some games like the Oracles, but we don't know how comes back to life prior to ALBW and Zelda 1, for example. All we can do is theorize, like SMS and I were doing.