The detailed timeline, when it came out, revealed a combination of failures on the Baltimore bridge ship. It had a complex electrical system, with 2 different voltages of AC as I recall, and some DC connections, batteries to start it. Start up takes about 20 minutes. There is redundancy in the electrical system with a web of cross connects, inverters, and buses to route power as needed.

But it lacked redundancy that night, as one generator was out of service, and had been out for some time. Something tripped a breaker, and power failed at the worst possible time, 10 or 15 minutes before passing under the bridge. Mistakes were made by the crew, putting the non-working generator in line to deliver power... The big engine died completely and there was no longer time to go through the start up sequence.

The harbor pilot called the harbor master, giving police about 5 or 10 minutes to clear the bridge. Unfortunately there was a maintenance crew out working on the bridge, and not time enough to warn them.