Get the AMLGX "box" image from https://test.libreelec.tv/ .. write to SD card and then edit uEnv.ini to set the dtb name (do not rename the dtb to dtb.img). Insert the SD card and trigger recovery boot again so the LE bootscripts are loaded (else you have CE scripts which look for different files). If all is well it will boot. The "meson-gxm-q200.dtb" device-tree exists and should support most hardware.
perfect - got it - will give that a go
appreciate the help 
Nightly images use Kodi Nexus (20) not Matrix (19). The images are not perfect but quite usable on S912 hardware as long as your media needs are not too exotic.
awesome!
i am using a CoreElec branch for the amlogic boxes (9.2.8) but it does not support Kodi 19 - and doesn't lock like its going to - but i need it for some addons which no longer work on 18. no special media requirements.
I'm assuming addons that work on 19 should work on 20 also - or at least will be worth a try
can anyone point me to a how-to for installing the LibrEelec builds on these boxes - i gather its a bit different from CoreElec - but its a while since i have dabbled with it
my box appears to be an old Edal T95Z plus ( 2g RAM 16g ROM) and runs ok with the "gxm_q200_2g" device tree file with CoreElec
i haven't read the whole 18 pages of posts - but was hoping for a simple answer to the question:
can we run Kodi 19 on the amlogic S912 boxes with any of the LE nightly builds
