The "Remote Control Buttons" app is worthless, leaving the remote itself rendered half useless. The buttons in the app in no way match the real buttons.
I must say, that CoreElec is fast & responsive as hell. But then there is a Dolby Vision problem, as I learn here. That's why I wanted to try out the dualboot.
[EDIT] Just read your edit. How did you succeed? Putting the OTA zipfile on USB stick and run update from file?