from machine import Pin
from utime import sleep

led = Pin(15, Pin.OUT)
led_onboard = machine.Pin("LED", machine.Pin.OUT)

led.value(0)
led_onboard.value(1)

while True:
  led.toggle()
  led_onboard.toggle()
  sleep(0.5)
BOOTSELLED1239USBRaspberryPiPico©2020RP2-8020/21P64M15.00TTT