Lights will not go on and GFCI outlet not working.

Hi. I’m baffled. The pool lights will not go on. There is a click sound in the AquaLink box. The GFCI outlet connected to AquaLink RS doesn’t give electricity to either plug. I replaced it…same issues. Voltage tester showed power (pic). I flipped the breaker several times. But test and reset buttons doesn’t work. There is a PX100 transformer. That’s mystery box to me.

Any thoughts on what I can try?

All the best.

Jim