I tried these parameters but they seemed to be ignored.

Not sure why there is /boot/vc/config.txt and also /boot/efi/config.txt

# Disable the power led
dtparam=pwr_led_trigger=none
dtparam=pwr_led_activelow=off
# disable wifi and bluetooth
dtoverlay=pi3-disable-wifi
dtoverlay=pi3-disable-bt