A friend had painters working at his house and they painted over electrical outlets and switches. They agreed to replace same. When they finished the replacement of wall outlets and switches he noticed that a ceiling track light wouldn't turn off from the wall switch. He was able to turn off the switch at the breaker. He also disconnected the switch and removed and capped all the wires but the ceiling fixture stayed on unless he switched off the breaker.
I went to his house to troubleshoot and determined that the black and white wires at the switch box were both hot by metering both to the grounded box. Both metered 120V. We went and tested other outlets that had been replaced and I found two with ground and neutral connections reversed, but these were on a different circuit from the ceiling fixture. Fixing these outlets had no effect on the "always on" light fixture. All of the wall outlets in the same room/circuit were tested and all seemed normal, i.e. hot was hot and neutral was neutral.
Any ideas on how to locate the source of the hot neutral to hopefully repair the ceiling fixture? The fixture is mounted on a high ceiling and surface mounted conduit runs back into a soffet housing an airconditioning duct. Working at the fixture itself will be difficult.

Each outlet that has been changed needs to be opened and checked for miswire. Even if it tests OK with a meter. Clearly something has been connected wrong in one or more of these outlets.

I can only imagine what else is wrong after finding the two neutral/grounds reversed.

While your at it, check each outlet for good splicing and screw connections, I wonder how many have poor connections.

I doubt there is any problem at the light, so accessing should not be a worry.

Sounds like a combination of an open neutral and a miswire. Check every switch also, as here is where you will find white wires that sometimes need to be hot feeding a switch, and after the painters that should not be playing electricians may not have noticed and treated it as a neutral.

Every outlet and switch needs to be opened and all the wires need to be rung out to determine their purpose and put everything back the way it was.