Hacking PA and robots/turrets ignores the keyword that prevents you from hacking the same PA/robot/turret again, but I also had to add a check so you couldn't hack power armor on a dead npc, just to avoid problems

There is no delay after a failed override/hack, though it won't show if the npc wearing PA is in bleedout from having the PA explode and the NPC is also marked essential.

If you intend to do the BoS questline, I strongly advise not overriding Proctor Ingram's PA, as the quests she's involved in can stall if she is out of her PA.