i guess kodi 18.9 for Minix X8 is possible but we need to stay to with LE9 which was the latest supported LE version for our amlogic box.
i have to admit that i'm using now an apple tv box and it does wat i need.
Trying to put LibreELEC-X8-H_Plus.arm-LE9-Kodi_18.6 onto a X8H-Plus. Image written okay, renamed boot.scr.
When booting I get to recovery with "Cannot load volume /misc!" at the bottom - but looking at the .img contents I don't see this...
I actually see I posted back in Jan about this, and one suggestion was to unplug the remote which I did with no luck.
when you boot with the reset switch pressed, it will not go to the Android recovery process.
In fact you won't notice anything except that your box will boot "LibreElec" in place of Android.
i guess there's something wrong with the method you follow.
Be sure to burn the image with the LibreElec usb SD creator, press the reset switch a few seconds and release it.
edit : i will my images to kodi 18.9, it's the final leia version if i'm not wrong.