Living room circuit

My mind is not working tonight…
Inspected a house built in 1966. Most of the electrical was great, but one outlet in living room was dead, then 2 others showed ok with the tester.

When I check an outlet, often, I press the GFCI test button, just to see if it does something. One time I found a living room with GFCI outlets all around…
Anyway, these other 2 outlets were OK, but with the trip button pressed, the middle light and the Red light came on, indicating the Hot/Neutral reversed - only when the GFCI trip button was pressed in.
What does this indicate? Please?

It means nothing.

Built in 1966…I bet two things…the living room did not have a ceiling light fixture and second, that “dead” outlet is on a wall switch so a lamp could be plugged into it and when someone enters the room they can turn on a light (lamp) at the wall switch. See it all the time especially in older homes from that era.

I plug a tester into the receptacle then try all the switches at the entrance areas until I find the one that operates the receptacle, identify it to the customers.

Doug - that’s the 1st thing I try - the outlet was dead - not controlled by the switch. There is a ceiling fixture. I am sure that at some time, some wiring work was done as the kitchen and baths have GFCI outlets.

Then it is still easy to write up and let the electrician “finger it out”.

It indicates that your finger was on the “trip” button.