I think you missed a simple "nothing much happened" trick with the mine . . .

You could have simply had the lights flicker, then fail. Let the PCs panic (maybe even start shooting), then after a few seconds game time have the lights flicker back on and remain lit. And nothing AT ALL further takes place.

If they investigate, there was a momentary power surge than caused some automatic breakers to trip, then reset after a brief system self-check. :)

Richard Aiken

"Never insult anyone by accident." Robert A. Heinlein

"I studied the Koran a great deal. I came away from that study with the conviction there have been few religions in the world as deadly to men as Muhammed." Alexis de Tocqueville (1843)

"We know a little about a lot of things; just enough to make us dangerous." Dean Winchester

"It has been my experience that a gun doesn't care who pulls its trigger." Newton Knight (as portrayed by Matthew McConaughey), to a scoffing Confederate tax collector facing the weapons held by Knight's young children and wife.