One theory is looking like a Pilot or First officer suicide.

Nasty. If you're going to do yourself in, why take 241 other people with you?
Reports indicate that the fuel supply switches were both turned off shortly after takeoff (but were both in the ON position at the time of impact).
Apparently, those switches cannot be moved without deliberate action by the crew.
The engines were therefore starved of fuel very shortly after takeoff and one of the crew members asked the other if he had switched off the fuel but this was denied by the other.

The engines were then set to restart by one of the crew but there was insufficient time to gain enough thrust.
Blimey, not the first time a pilot or first officer has deliberately crashed an aircraft.

On the other hand, did one of them try to cycle the engines after engine failure and it was just a tragic accident?