Bit of an odd one, isn’t it? The surviving passenger said he heard ‘a loud noise’ after takeoff, but I’m not sure if that’s true/relevant…that could be anything.
Seems that the pilots had control of the aircraft…a double engine failure would be very unlikely. The flaps thing is a distinct possibility, hard to tell if the plane has 5 degrees of flap on those grainy videos but the way the aircraft behaves, it does look like it rotates and just stalls almost instantly. I believe that the 787 has a takeoff config alarm if you take off without flaps (the 737 certainly has)…if that’s the case then I’m not sure they could takeoff without flaps. Possibly could have retracted the flaps instead of the gear? No idea how a pilot could make that mistake mind, but these things do happen with fatigue etc…
I’m just staggered that someone survived that fireball and hitting into a building…10 hours of fuel onboard plus contingency.