I have a front yard light pole and the sun sensor broke which the light always stayed on.
Finally we had a new sensor installed and now the light doesn't go on. Our outside GFI keeps tripping. Reset button on top which is pushed out and when I push it in the light flicks on but the button pops out. The below test button stays pushed in.

There may be an issue with the sensor. GFI can have false trips due to the electronics in some devices. You may need to try a different sensor. The lights do not need to be GFI protected, so perhaps the lights and sensor can bypass the GFI.

Try disconnecting the sensor and bypass the wiring so the light is fed directly by the GFI to prove the sensor is the problem.