Thank you all, I understand that.
I do not really understand how the instantaneous destruction of power occurred?
2:57 power = 69%, 1s and shield shutdown !
Most modules can malfunction any time they fall to 80% integrity or below. If your power plant malfunctions, it's output falls to 40% for five seconds before returning to normal.
There is a very good reason why my hybrid corvette runs an armored PP and has power priorities setup so that it's thrusters, FSD, shields, AFMU, and power distributor all function at 40% power output.
In the case of a more shield focused vessel, keeping all of that active during a malfunction usually isn't practical, but you can at least make sure the shields don't lose power.
Wasn't he just hit by some reverb torps or mines by the FdL's wingmate?
He was, but the fact the shield starts to regenerate not long after indicates that it was a PP malfunction, not destruction of the shield generator (shield gens never malfunction), that caused the shields to fail.
It's certainly possible to quickly repair a destroyed shield gen to a few percent integrity to allow it to be powered up and regenerate (my own vette has been in fights where the shield gen has been destroyed, repaired, and shields restored, multiple times), but I do not believe that was the case here.