HI Stephan,
please use below code. thanks.
[code]
import time
from pixel_ring import pixel_ring
from gpiozero import LED
power = LED(5)
power.on()
pixel_ring.set_brightness(10)
pixel_ring.set_color(0,255,0)
time.sleep(3)
pixel_ring.off()
power.off()
[/code]