On DB410C the user LEDs are controlled by the Linux LED sub-system (I
think if you try to access them as GPIO they will appear to be busy).
Unfortunately it doesn't look to me like MRAA has any support for the
Anyhow, you can do something like this (or the equivalent in C) to
control the LEDs:
echo 1 | \
sudo dd of=/sys/class/leds/apq8016-sbc:green:user2/brightness