In order to make your power button on ODROID-U3 work, you may have to install
acpid at first. Otherwise, the power button won't even work.
I use latest Debian Wheezy on this board while MATE as the desktop environment. However, after installed
acpid, the system is to shutdown immediately when I press the power button.
Let's see what
acpid does when power button clicked, the contents of
/etc/acpi/powerbtn-acpi-support.sh which is basically to call
/etc/acpi/powerbtn.sh if it exists, or
/etc/acpi/powerbtn.sh.dpkg-bak if the former one doesn't exist, or shutdown directly if it doesn't exist neither. Unfortunately, there is no
Since we figured it out, we can modify the behaviour so that it'll prompt a shutdown dialog instead of poweroff without question. Add
/etc/acpi/powerbtn.sh file whose contents are
If you're using other desktop environment, you need to replace the second line to other command. And, remember to add executable permission by command
sudo chmod +x /etc/acpi/powerbtn.sh.
After this simple change, the power button should work expectedly now.