Just on the issue of windshield failure, there is an interesting digression on the manufacture of the above, in the TSB report pertaining to
AIR FRANCE
BOEING 777-228ER F-GSPZ
CHURCHILL, MANITOBA 290 nm NE
17 OCTOBER 2002
where an arc resulting from overheating in the J5 terminal caused a small fire and the windshield to crack.
I won't link as I can't get it through moderation,
but anyway comms were not affected (obviously)
so if this were a contributing factor in the present case we would need to find a reason for lack of comms.
ETA (from the report)
'Boeing has undertaken a program to redesign the window terminal block to eliminate the screw connection. The new window blocks were scheduled to be incorporated into Boeing 777 aircraft, Line Number 471 (delivery date February 2004). The new design incorporates a locking pin/socket, which will address issues concerning loose or cross-threaded screws and inset ferrules. All Boeing 747, 757, 767 and 777 windows delivered thereafter, either on new aeroplanes or as spares, will have the new terminals installed. Boeing intends to deliver spares in kit form with the new wire end terminals included. The operator will have to remove the existing wire end terminal and splice in the new one when replacing windows on existing aircraft. The intent is to eliminate concerns with arcing at the window power terminals.
Boeing released a Fleet Team Digest article to B757 operators in May 2003, discussing terminal arcing and overheating. The article detailed actions to incorporate re-designed terminals into the affected cockpit windows.'
I'm not sure how relevant this might be, but it looks like there was no retro-fitting of the new system so as far as I can figure out, 9M-MRO will have had the original sort.