Hello MLJ,
For switching to OpenElec side from Android side you will need to click on the app named as Switch To OpenElec.
You can find the app in your full list of apps.
You can access your full list of apps by clicking on Circle with 6 dots near the bottom of the Home Screen (Screen where you see Settings, XBMC Media Centre, Clock and other icons)
Then scroll down and find Switch To OpenElec app and click on it and it will take you to the OpenElec side.
Check this video our on setting up the Open Elec side:
(Above video also cover formatting HDD which is necessary for HDD to be recognized)
Additionally you can also watch this video on formatting HDD in OpenElec side: