Successful installed (to internal) latest version of CoreElec on Android TV box M9S Pro16 (1 gig ram/16 gig ram) using the following:
Device = X96 (S905X)
Ram = 1G
DTB = gx1_p212_1g
Used Win32 Disk Imager to create SD from image
Followed by putty to ssh into box, installtointernal
Works perfectly. Using the official Kodi iPad/iPhone remote app, since I lost my ir remote when we moved to new house.