Found some Infos when using CoreELEC elsewhere
``````´´# set gpiopower in /flash/config.ini
# Power Off and Wake Up using GPIO Key Button
# Valid options for Odroid N2/C4 are 476,477,478,479,480,481,483,484,485,486,487,488,489,490,491,492
gpiopower=479
But how to get it work on an N2+?
The LibreELEC wiki has infos about adding entry's when using a RasPi
https://wiki.libreelec.tv/configuration/config_txt
Of course, when running a N2+ there is no config.txt to modify ,,,,
So finally the question is how to get a gpio power switch recognized?