I have a 4k movie that plays well under Android on the Nvidia Shield, but crashes the box when using CoreELEC on my Mecool M8S Pro and my Mecool KM8. Both boxes completely power off. I tried running the movie from my Synology NAS and from my new 8 TB powered external HDD, with the same results. All of my Blue-ray Rips play without issue, only this 4k movie causes the issue. Here is the mediainfo for this movie.
Complete name : \DS216\Video\BlueRay_Movies\Action\Skyscraper (2018)\Skyscraper (2018).mkv
Format : Matroska
Format version : Version 4
File size : 52.2 GiB
Duration : 1 h 42 min
Overall bit rate mode : Variable
Overall bit rate : 72.9 Mb/s
Movie name : Skyscraper 4K
Video
ID : 1
Format : HEVC
Format/Info : High Efficiency Video Coding
Commercial name : HDR10
Format profile : Main 10@L5.1@High
Codec ID : V_MPEGH/ISO/HEVC
Duration : 1 h 42 min
Bit rate : 69.1 Mb/s
Width : 3 840 pixels
Height : 2 160 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 23.976 (24000/1001) FPS
Color space : YUV
Chroma subsampling : 4:2:0 (Type 2)
Bit depth : 10 bits
Bits/(Pixel*Frame) : 0.348
Stream size : 49.5 GiB (95%)
Language : English
Default : Yes
Forced : No
Color range : Limited
Color primaries : BT.2020
Transfer characteristics : PQ
Matrix coefficients : BT.2020 non-constant
Mastering display color primaries : Display P3
Mastering display luminance : min: 0.0050 cd/m2, max: 1000 cd/m2
Maximum Content Light Level : 1000 cd/m2
Maximum Frame-Average Light Level : 986 cd/m2