Skeeter1 - it's an interesting theory but I really can't see it. This is a 777 we're talking about. You can't land that in a jungle clearing, you need a major airfield and you're only going to be able to land there incognito with the backing of a national government, in which case why bother hijacking? - just help yourself to a government plane. Anyway, which government would support this? - as you say, you'd be at major risk of a visit from a few hundred thousand heavily armed Chinese guys.
Do you think the pilot had back-up? If not, why wouldn't the crew break the door down? Why wouldn't the passengers make phone calls?
I suspect it's just a terrible accident.