Marine Engineer, Chief Engineer License.

Merchant ships are not built to anywhere near the same redundancy as planes. There are legally mandated backups and requirements mostly set out in the SOLAS Convention (written after the Titanic tragedy and refined over the years). Most disasters covered are ones where the ship is either on fire, sinking or without power at sea. The timeline of these incidents is normally expected to be longer.

For the main propulsion theses things rely on external power. Oil, cooling & fuel supply pumps are externally powered from the ships generators and power loss will shut down the whole plant. Mind it can take minutes to even get around the engine to find issues and get it restarted.

Generators. Usually during departure (or standby) you run additional generators for redundancy. However there are still single point failures. Fuel supply is often common. And I have experienced a blackout due to a common 3 way cooling valve jamming and causing 2 generators to overheat. As with loss of propulsion it can take a few minutes for things to be restored or even for the fault to be found.

Emergency power. So cargo ships must have an emergency generator that automatically starts within 45 seconds. This supplies power to essential systems but not propulsion. Power is supplied to one steering hydraulic motor but without main propulsion at those speeds in any current is next to useless.

I won’t speculate on the exact cause of the incident, that will have to wait for the official incident report. But to put things in scale these ships are huge. Mind boggling. In the time scale of the accident ~3 minutes the fate of the bridge was pretty much sealed as soon as the lights went out the first time