She wasn't on shore power so had a boiler running to provide power to the ship. As was mentioned they were going to switch boilers at 0800 and thus had the second boiler heating up at the time of the attack. Of the ships that made it underway that morning all were in the same situation.
All the ships who made it underway that morning did so because of young leaders taking initiative and acting on their own in face of extreme conditions.
In a couple cases it was relatively new Ensigns who were standing watch, because that's who draws duty on Sunday morning in port, and stepped up and made critical decisions instead of waiting for orders from superiors.

Yes SOME still did, as the ignition charge for the main powder. Arizona used an older gun and charge, an had a sizeable blackpowder magazine still aboard the morning of Dec 7th, where a hit in the area of A/B turret is a good candidate for what actually destroyed her. The old theory about a bomb down her main funnel is completely debunked, and there is quite a bit of physical proof one of her main magazines did not detonate.

Drachinfel's video on the subject is an excellent summation, and give his sources as well. The evidence does point to the blackpowder magazine she had aboard as the source of the explosion.