Looking at your screenshots, I believe you might've run out of fuel, not had a power management issue. In future, I'd suggest keeping an eye on it. Fuel up at stations, or equip a fuel scoop, and scoop from stars (Not all are scoopable, only classes O, B, A, F, G, K, and M).
Also, there is a player-run service to help rescue stranded players. Check out fuelrats.com for more info.
Just to the right of your power distributor bars, and just above the mass lock indicator is a bar marked "Fuel". It appears empty, and the fuel usage shows 0.00/h.
As the others have said, though, a damaged powerplant won't output as much.
I hope this helps!