We were gone from our house for 6 days last month.
When we returned home I noticed that a wall dimmer light switch wasn’t functioning in our pool room (containing a small swimming pool).

The GFCI (ground fault circuit interrupter) outlet for the power leading into the pool room would not initially reset.

I tested wall light dimmer switch with an ohm meter that indicated it was faulty. So I replaced it with a new wall light dimmer switch.

Then I reset the GFCI outlet and I thought all was well. But each time that I plug something (like a night light) into the GFCI outlet the GFCI outlet shuts off.

Apparently all works well as long as nothing is plugged into the GFCI outlet.

Is the GFCI outlet faulty? It’s 20 years old.

Is there likely some other problem?

Is it time to call a professional electrician?

Thanks!