@ Chronus: "It is inconceivable that between 1720:30 and 1721:13, in 73 seconds, a failure of all electronic/electrical systems may have ocurred so as to render all communication systems and life support systems inoperative and ....."
Some kind of outstandingly & extraordinarily different fault has to rise which could be 1 in 1000 - some thing that aviation industry encountered first time !
Or else, some one "forced" that fault ............. either in MAS ..... or in cockpit ...... or perhaps under the cockpit.