Safe Mode comes before DFU.
Release the SETUP button as soon you see the first magenta blink after hitting RESET.
You mean cyan breathing stops, or are you refering to the blue D7 LED?
And I guess that’s the solution to your riddle
// that's from the weather station code
//Get readings from all sensors
//Print to console
//Send data to Weather Underground
//Power down between sends to save power, measured in seconds.
System.sleep(SLEEP_MODE_DEEP,300); //for Particle Photon // <--- that's supposed to switch the LEDs off!!!!
//Spark.sleep(SLEEP_MODE_DEEP,300); //for Spark Core
And did the blinking happen as expected, or did your blinky sketch just not stick and you were still seeing the effect of