https://www.bbc.com/future/article/20191108-the-switch-that-saved-a-moon-mission-from-disaster​

It’s only later that he discovered the rocket had been hit by two lightning strikes. “We generated our own lightning,” says Griffin. “Ionisation of the extremely hot exhaust from the Saturn 5 created a ground.” In effect, the rocket became a giant conductive rod connecting the electrically charged clouds with the Earth below.

 

If you can find it, look around for Pete Conrad's (Apollo 12 commander) story on the event. With the systems dark during restart, as he put it he grasped the abort handle having ' my hand on about 20 million dollars of goin' to the moon machine that I didn't want be the one to end' I think it was John Aaron, a mission EE, that remembered he'd seen something like the displays after the stricke during sims. It took awhile but eventually they figured out to set a systems channel to the backup. When the lightning struck and he saw similar displays, he offered 'Set SCE to AUX' and that got things back up.
Conrad was a kick. Stepping off the lander and being a compact fighter pilot he radioed back 'Whoee! That may have been a small step for Niel but it was a big 'un for me!'
Those guys were sumpin' special.