FlashForward finished the other week, in a bizarre undead state. On one hand, the cliffhanger finale closed two or three plot threads while opening ten dozen or so new ones, leaving the central mystery of the series unresolved and plenty of material for the second season to chew through.
On the other hand, the series has been cancelled and there won't be a second season.
What a waste of time, eh?
Aside from the boring and pointless Keiko/Bryce storyline, we both actually really enjoyed this series, so I'm a little sad that I'll never find out what happened - but not that sad, as I strongly suspect the producers never had a specific ending in mind, preferring to play the cascading mysteries game, keeping it open-ended and stringing the audience along for as long as they could.
In order to provide fans with closure, I have taken the liberty of finishing the plot for them:
It's all the CIA.
Jericho is exposed as being the strong-arm of President Segovia, who has been assisting the Global Blackout Conspiracy. He is deposed and the vice president takes over, as foretold. He, like Hellinger, initially rose to power by using information about the future gained in the Red River experiments. Jericho footsoldiers are the pig-masked gunmen who raid the FBI building, and also the three-star tattoo men. The key is that Hellinger is actually a CIA special agent, and the Global Blackout Conspiracy is a CIA plot to save the world and make a buck while they're at it, which is the story of America anyway.
The towers in Somalia in 1991 were prototype cellphone towers. The global blackout was caused by a signal generated by the worldwide cellphone network, amplified by the NLAP accelerator. The cellular industry is actually controlled by Hellinger.
The first flashforwards at Red River were a CIA experiment to gather information about the future, for their usual Secretive Purposes. Dyson Frost was the chief strategist and future-knower. Vogel knows all this, which explains his seeming lack of motivation to pursue the most obvious lines of investigation. Janis is thus an unwitting triple-agent, as the CIA are the ultimate source of the blackout conspiracy. Lita wheels Janis away in the last episode to ensure she doesn't risk exposing the CIA connection.
While the CIA were gathering information about the future at Red River, Frost discovered a disaster due to occur in 2016: a gamma ray burst causes interference with the global telecommunication system and kills everybody exposed to an electronic information source. He realised that the only way to prevent this future occurring was to ensure everybody in the world blacked out at that moment. He fakes his own death in order to work uninhibited on a solution. He gives future stockmarket information to Hellinger who is able to make the billions required to bring about the global cellular communication revolution of the 1990s, thus installing cell towers globally.
The Antikythera mechanism was not used to generate the blackout; it was merely Dyson Frost's way of indicating the use of technology that is ahead of its time. Neither is Simon's "pulsed laser for a plasma afterburner" cell tower design the source of the blackout; it is merely a scale-up tool for the device invented by the CIA. Dyson Frost gave himself multiple FlashForwards in order to explore possible futures where he met Simon and learned the design from him, in order to build the Somalia towers a year before Simon invented them.
In fact, Simon and Lloyd are involved purely as inventors of scaling-up techniques, and much of the CIA's efforts revolve around maneuvering these two into positions where they are able to design, build and calibrate the NLAP accelerator by the year 2009. Somalia was a test of the scale-up system to prove it could work at all. NLAP was a test of a scale-up system to prove it could work globally. The second global blackout that occurs on April 29th 2010 is an attempt to make the blackout last long enough to keep people safe during the disaster in 2016.
The alpha rings are necessary to keep the unseen operators of the blackout device/cellphone network awake so that they can turn it off; otherwise everybody would stay blacked out. Simon is kept awake during the first blackout to keep him involved in the conspiracy, in case they needed him for further calibration work.
Dyson Frost tries to leave the CIA conspiracy because he knows the CIA will inevitably assassinate him in order to keep their work secret, as they want to retain blackout technology for their own purposes even after the disaster in 2016 is averted.
The woman in Hong Kong is also CIA, and warns Dimitri of his fate in order to ultimately bring about the confrontation between Dimitri and Frost which they know will end up taking care of one of them.
Mark Benford does not die in the explosion at the FBI; he goes underground to Afghanistan to join Aaron in the hunt for the conspirators; Charlie's second flashforward of her saying "They found him!" means Mark and Aaron both come in from the cold when the discover the truth that the CIA are actually trying to save the world, even though they kill millions in the process.
Only when Mark agrees to remain silent and effectively join the conspiracy do they stop trying to kill him. He feels free to join them because Olivia and Lloyd have already got married. Gabriel McDow was chosen as the best man, as he had the biggest hippocampus. Nicole becomes romantically involved with her rescuer. Their on-off will-he-drown-me-won't-he relationship dominates most of the second, third and fourth seasons. You won't have missed anything.