ANAKIN SOLO was chilling in his room with Fiver (and IDK? Nico?). Right before everything happened he'd have sat straight up with a sort of chill. After everything turned off, his first worry would be to check in with people - i.e., like make sense he can feel his mom and grandmother, grandfather, etc in the Force, then grab his lightsaber and go out to see if he can help. When there's no sign of immediate danger, he'll probably end up trying to help with ship's repairs.
HERA SYNDULLA was up by the pool tonight. When everything stopped, she would have gotten very wary and immediately headed back towards her room to check on Sabine, but also would have fun a full sweep of whatever decks she was on looking for trouble on the way back down. Since that is also her deck for patrol, once she was certain things were all right, she'd probably start looking around there for any signs of trouble.
CREDENCE BAREBONE was in his suite and he momentarily freaked out. Like Obscurus is there, and surface ready, sort of freaked out. As soon as nothing terrible followed the lack of lighting he probably went to check on Helena and Luna and Albus. He feels completely inept for doing things to help, so if Albus needed someone to help with Helena so HE could do things, Credence would do that.
SEVERUS SNAPE was also in his suite reading. As soon as the lights went off, he got up, wand out, and went to see what was going on around the ship. He likely ultimately ended up on his patrol deck and will make contact with that deck's team probably once the network is back up.
KYLO REN like Anakin, had a sense of something happening before it did. I think it's likely he was with Eliot, but I'm not certain if that was in his room, or elsewhere in the ship, in one of the lounges or something. He would immediately do a sweep in the Force looking for any immediate danger, particularly would check on the well-being of his mother, father, and grandmother, check his lightsaber, and will probably end up on patrol.
MAX GUEVARA says fuck EMPs. Fuck them. Seriously. She knows how this goes with people not food or transportation or whatever. So she pretty much spent time hiding stuff in her room and taking care of her own shit before she went out. She might have ended up in the kitchens helping with food, cause if nothings invading, that's probably first priority.
CHARLIE WEASLEY #2 was definitely in a lounge. He's got his wand, and would probably head back towards his room unless he was drug into helping with something by one of his brothers.
POE DAMERON was out with Finn and BB-8 walking around. The latter we're going to say sort of froze up, and then restarted - cause Poe loves his droid like whoa and EMPs are sometimes used as weapons, so he's put in contingencies. But because of that Poe has a pretty good guess what just happened. His first instinct will be to look for attack, but when nothing's immediately available he'll probably want to check into the room, find his blaster and see how badly it's fried (:|) and then look to see where he can do help.