CEC is one of those 'standards' that has many implementations, and apparently with lots of subtle differences per TV manufacturer (and maybe even per TV brand/range).
It's best to turn on the TV first, and then the LibreELEC box, so the HDMI handshake can be fully executed. AFAIK, there are no CEC commands possible via the busybox backend.
You could try and implement the TV's EDID into LE. Read here: Configuring a Custom xorg.conf - OpenELEC
Anything is possible, but we haven't received large numbers of complaints on the Backup/Restore function.
If there is, it's still very unlikely that something like a 7.0.3 release will be done, as just about everyone is focused on Kodi 17 (Krypton), meaning LibreELEC 7.90.007 currently.
A log file is always helpful as Kodi client machine info is added. AFAIK, no log entries are made via the B/R tool.
Get a OLED TV screen first, if you want to check black color screen values... /me runs 
Just a tip, we're at 7.90.007 already. Shouldn't matter much on your topic, but it's good to know.
Most likely you tried to migrate to LibreELEC using the wrong .tar file.
We'll need lots more details as DaVu already pointed out.
Changing HDMI cables would be a last resort. I assume you did select the HDMI port in the Audio Output section (GUI level Advanced/Expert).
Perhaps you can install Ubuntu+Kodi instead, and use the easier GRUB2 boot loader. You can then install LibreELEC next to Ubuntu manually, turning the pc into a multiboot machine.
Thanks for the quick answer. By the way, any optimization I could do in the Bios before? Chris
Probably not. Make sure you use AHCI on the disk controller.
Without any details/specs on your Intel PC there is not much else to say.
There is no way that some software package like Kodi will magically turn your NUC into having GPU hardware acceleration capabilities for FullHD or 4K HEVC video files playing without a glitch. You will definitely have to buy newer hardware for that. Starting with Braswell or Skylake, or the latest Apollo Lake NUCs. Or a bit cheaper (and smaller) alternative, a S905 chipset based Android box like a Wetek Hub.
It's still enabled by default as a souvenir from the big old CRT screens. But the TVs of today each have a setting for it.
I can understand the throwing-together of old parts into a htpc box, but LibreELEC (as was OpenELEC) is not in the habit of supporting old(er) hardware for too long. We base LibreELEC on the latest 'bleeding edge' version of Linux, being 4.8 now afaik, and the same goes for the video card drivers. Since AMD has a somewhat 'workaround' video driver developed by the community, results are mixed. Even the latest/newest AMD APU are not recommended for Linux HTPC usage in my view. A Windows based AMD HTPC is a different matter.
Options? Use the AMD box as a NAS or file server, and get a simple Raspberri Pi 3 as a Kodi client. The RPI is widely supported and 'comparatively' pretty solid for what is basically a 2009 smartphone video player. If you have 4K video ambitions, look at S905 based boxes like the Wetek Hub. Or wait a couple of months for the new Asrock motherboards with Apollo Lake, f.e. the J4205.
AMD Turion... A CPU/GPU dating possibly from 2007. 
AMD has always been a problem child since a long time because AMD had no desire in properly supporting the Linux cause in terms of drivers.
I take it you have tried all audio outputs possible in the Kodi GUI?
Are you getting proper audio from the analog output?
Unfortunately, ccloud.tv is one of the addons that is on Kodi's blacklist of addons considered illegal. So, support ends here.
Some machine details would have been nice.
All problems/bugs are to be accompagnied with at least a Kodi.log file.
Read for more details: HOW TO:Provide Logfile - LibreELEC
It's good that ATI only sold exactly 1 video card, so the problem shouldn't be hard to find.
There is a URL for that: HOW TO:Provide Logfile - LibreELEC
In the latest Alpha 007 there is also a log tool implemented.
Make sure you have a decent full backup first.
Start upgrading with this .tar : LibreELEC-Generic.x86_64-7.0.2.tar
4KSamples - Free Downloadable 4K Sample Content (not that many videos)
Some people Kodi users need to work more on their common sense skills.
Thread is closed (again).
