For those that don't know, the B737 has a trimable horizontal stabilisor and hydraulically actuated elevators. It also has a trim tab on each elevator. In normal hydraulic control this tab is locked and in line with the elevator. With no hydraulics in manual control, it is unlocked and works as a trim tab. The pictures show that the trim tab actuating rods and attachment on the trim tab is missing, so the trim tab would have been flapping. This would have ben the exit point for the lightning, wonder where the entry point was?