Shamelessly stolen from https://community.ui.com/stories/Repurposing-a-second-UniFi-Cloud-Key-as-a-DNS-Recursor-Radius-and-NTP-server/56605e0f-401f-4397-8c05-5b1cbe118bf6

led-tool

# vi /sbin/led-tool 
#!/bin/bash
# Shamelessly stolen from https://community.ui.com/stories/Repurposing-a-second-UniFi-Cloud-Key-as-a-DNS-Recursor-Radius-and-NTP-server/56605e0f-401f-4397-8c05-5b1cbe118bf6

if [ "$1" == "blue" ]; then
    echo "Enabling steady blue LED"
    echo 0 > /sys/class/leds/ubnt:white:dome/brightness
    cat /sys/class/leds/ubnt:blue:dome/max_brightness > /sys/class/leds/ubnt:blue:dome/brightness
elif [ "$1" == "white" ]; then
    echo "Enabling flashing white LED"
    echo 0 > /sys/class/leds/ubnt:blue:dome/brightness
    echo timer > /sys/class/leds/ubnt:white:dome/trigger
    echo 750 > /sys/class/leds/ubnt:white:dome/delay_off
    echo 750 > /sys/class/leds/ubnt:white:dome/delay_on
else
    echo "ERROR: Unrecognized led $1"
    exit 3
fi