Hi,
i have to admit, copying files with dd, inserting the card, booting adding a smb video source (gbit ethernet, but files are comming from a 2TB drive with 7200rpm which is about two years old.
can run hdparm later to test for speed but it will probably do ~100mbyte/s read spead)
attaching the air mx3 remote, playing the first movie fast a really fast setup - good job 
but playback is not as fluid as i hoped plus my TV says that i should check the power when playing some movies - no input signal from the source.
after pressing play i see a black screen with a light white circle in the middle that is apparently loading the movie - it does about 3 turns.
switching sources on the avr brings back a black background with the above circle for a few seconds, then TV says its off again.
in parallel im connected via ssh to the coreelec box, in the log i can see that remote signals are still processed but the back button on the “kodi remote” never gets me back to the menu nor do i see the movie playing.
in the beginning there is sounds for a few seconds and then even that stops.
i am able to enter reboot via ssh and coreelec reboots.
this is the beginnging of the log:
and this the rest:
look at the second file first, at the end theres maybe a output problem.