Been an long time user of Libreelec/Openelec on RPi.
Recently discovered the wonderful CoreELEC (you guys are not easy to discover on internet). As per your install guide, I configured it on my old Odroid C2 and it’s been working great. C2 is running with 16GB eMMC, directly connect to 4K Android TV over HDMI, all CEC settings on TV and Coreelec are defaults, except the auto on/off for devices on both are disabled.
My only problem is when devices restart after a power failure (or UPS failure/disconnect mains). The TV stays in standby while Odroid C2 restarts. When I power on TV and switch HDMI to Coreelec, the screen is blank, but looks like Kodi is loaded as I can hear click sounds when I use remote. Power off/on, changing source doesn’t help. Kodi is set to 1080p/50, 4096 resolution is not whitelisted. I could login to Coreelec on SSH and issue a reboot command, but surprisingly it doesn’t help either.
The only way to get back Kodi/Corelec screen on TV is to disconnect Odroid power and reconnect.
Appreciate any help.