you need 3 files on your SD card, the actual .zip from Demetris, factory update script and a recovery.img.
I found it easier to flash an old openelec that I knew flashed (even if WiFi didn't work 😉) then put Demetris update zip onto a USB flash drive and used kodi file manager to transfer it to storage/.update.
Tbh I have never flashed any of Demetris files only ever used the update tars.
Probably doesn't help you much lol
All the best
EDITED: you could try taking the factory update script and recovery.img from your android ROM put these 2 on The root of your SD card along with the correct zip from Demetris