A screenshot can be usefull when trying to troubleshoot issues. There is no straight forward way to take a screenshot in CoreELEC.
CTRL+S
Using one of the following:
ctsl+s
assigned to a Remote Control Unit buttonThe Kodi Keymap Editor is a GUI for configuring mappings for remotes, keyboard and other inputs supported by Kodi.
kodi-send --action="TakeScreenshot"