What would you do as pilot of a 777 (or comparable aircraft) if faced with a 'significant' electrical fire in the exact position south of Vietnam where MH370 deviated from course?
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.
I would keep well away from undocumented home made procedures. These are complex machines and you can run into pretty severe unintended consequences if in the spirit of the moment you go off piste. Avionics fire, fumes, smoke is a well covered scenario with well defined containment actions planned by boeing engineers and test pilots with far more in depth knowledge and time than I would have if suddenly confronted with the problem.