It's a chinese mini pc, so iGFX is all there is.
They slapped in a development/debug AMIBIOS with lots of options, and I explored all gfx&other semi-relevant ones but got no luck. I've also played with i915 module kernel boot options the people on the internet used to solve their Kaby Lake notebooks gfx-related hangs, but as you guess nothing helped.
Meanwhile I've tried a new Milhouse build with 4.19.7 and saw no improvement.
Cannot boot LE 8.9.007+ on Celeron 3965U mini pc system - it resets (boot cycles) a few moments after Libreelec logo is displayed, and build number appears on the top left of the screen.
I've tried both live and installed variants. Latest Milhouse build exhibits the same behaviour.
8.9.006 and earlier alpha builds, including latest stable 8.2.5, boot fine.
dmesg of successful 8.9.006 boot: https://paste.ee/r/9tqbv/0
Looks like it's not LibreElec's fauit. From what I see in github changelog, 8.9.007 moved to 4.19 kernel, and it is my problem. I've just tried ubuntu 18.10 with 4.19, and it won't boot as well: during Gnome Manager startup I see a similar momentary screen distortion and then it hangs. Duh.
