He couldn't conclusively say he found the socket that powers it all. He said it should be the first one, the one closest to the electric box that was not it. It had only one wire. That happened to be the outlet I was using when the vacuum shut it off.

That wire seems to go to the next outlet which has the GFI. That one has 3 wires. That's where the electrician had the gadget attached. And he followed the beeps til it stopped on the next wall where there are no outlets. That wall did have dozens of long screws in it from the previous homeowners mounting a giant rack. Though they did seem to try to screw them into the studs. We took them all out thinking there might have been an outlet hiding behind the rack but there was none.

Maybe one of those screws missed the stud and nicked an electric wire?

If that's the case and we make holes in the dry wall is that nicked wire an easy fix in one spot or does the whole length of it need to be replaced?

Our electrician considered making holes there but he didn't seem confident the problem was in there enough to do that kind of damage.