Turn towards the nearest suitable runway, run the appropriate checklist. Just as he would have practiced many times in the simulator during his career. The company simulator, not his own.
Indeed. Anyone looked into Langkawi airport as the runway he might have been heading to? To me this is the theory that makes sense..
Checklist also involves cutting electrical busses, refer to 1998 crash of Swissair DC-10 off Nova Scotia, where fire was the cause, and transponders and communications were shut off as they pulled the busses.
Climbing to FL450 also appears to me as an attempt to put out fire; hijackers climbing to FL450 do not make sense.