Last night we saw NTSB give a run down on what the VDR said but answer to your questions above and more will be when they download the contents of the plant automation data logger / alarm history. This will have or should have time stamped events like EDG start, bus tie open/closed etc etc including possibly some hints about the SSDG problem to begin with. A dying engine due to fuel Should see low volts, freq. over speed? High temp? So it seems patience is still required. Or some can speculate the engineers were tired so put it “on auto” and went to bed or the fuel was bad. Or many other things some more plausible than others.