Maybe it is a new box, but apparently its internals are not allowing LibreELEC to be installed seeing all your attempts. We can only do so much.
BTW, using screenshots of quoted messages and their links is not usefull. Those links cannot be clicked...
If all these solution do not work, it sounds like the end of the line for your TV box.
Solution: upgrade your iOS. 
New tricks are helping the Raspberry Pi's 2 and 3 play 1080p HEVC videos pretty well with the latest releases.
A moderate overclock will help as well.
I think the bell icon animation at the top is not that necessary.
It's a bit too much attention-seeking to me.
I think our userbase is already a little spoiled. Like students in a class, they are testing the (new) teacher.
As far as bug fixing goes, Kodi / LE plus others have responded very quickly overall. I can think of certain bugs or vulnerabiilities in operating systems that took even years to get noticed and fixed.
LibreELEC 8.0.2 has been announced, so off you all go to the download section(s). 
With LibreELEC is not just about the Kodi application, it needs to fit various types of hardware. It's very preferable to release LE 8.0.2 for all officially supported devices. Not doing so creates different problems, amongst other "Why is LE 8.0.2 released for that device, and not for 'my device'?".
So doing another LE release after a Kodi release takes a bit time. Kodi 17.3 was issued... May 25th. People are yelling for LE 8.0.2.
LibreELEC 8.0.2 with Kodi 17.3 is currently being tested. What is today's date again?
Not really. I'm guessing it's more a Linux brainfart that is misinterpreted within your machine.
How nice of them
Normally there is one output selected at the time.
Go to System / System Settings / Audio / Audio output device.
Make sure you have the GUI setting level to 'Advanced' or 'Expert' for full menu options.
Also get us a full kodi.log file (debug enabled) for the necessary hardware information.
"Best" is a pretty personal opinion of how a chipset or machine performs.
I hope you're not calling us lazy... 
Apparently Kodi 17.3 is also on the way, so we're waiting on that for now. Not to mention the other stuff that needs to be implemented and tested.
The Odroid C2 turned out to be a pretty solid choice, it is a benchmark of sorts towards other hardware.
Beauty is in the eye of the beholder as always. But yes, new software was needed, not in the least because of more and more spam attacks.
We have the inital LibreELEC makeup on this new forum, further cosmetic changes will be done along the way.
Are you sure you are not experiencing a DNS problem at your end?
I can access Github URLs just fine.
You can also have a look here for general information on hardware for Kodi:
( last libreelec)
That is not really a version number. 
You can always upload the kodi.log file, debug enabled, if you are unsure of all the specifications.
When i choose 'Sleep', pc act like its going to shut down, screen goes black, fans stops but after few seconds (1-3s) it back to the state before i clicked 'sleep'.
It's something that seems to happen to some other/older Intel-based machines too. I had it happen to one of my Kodi clients as well. It's been hard to pinpoint so far where the problem lies.
Are there any options in kodi preventing sleep mode?.
Sleep mode is not enabled by default as far as I know. You can set it to "Do not go to sleep". The same goes for the screensaver.
Apart from that, a 300W psu is much overkill for a simple 6-10W htpc.
A 40-60W pico psu is much more efficient and totally silent as well.
Noticing your installed repositories...
20:12:10.909 T:1961934848 NOTICE: ADDONS: Using repository repository.xbmc.org
20:12:10.909 T:1961934848 NOTICE: ADDONS: Using repository repository.aresproject
20:12:10.909 T:1961934848 NOTICE: ADDONS: Using repository repository.exodus
20:12:10.909 T:1961934848 NOTICE: ADDONS: Using repository repository.metalkettle
20:12:10.909 T:1961934848 NOTICE: ADDONS: Using repository repository.podgod
20:12:10.909 T:1961934848 NOTICE: ADDONS: Using repository repository.shani
20:12:10.909 T:1961934848 NOTICE: ADDONS: Using repository repository.xbmchub
20:12:10.909 T:1961934848 NOTICE: ADDONS: Using repository repository.schismtvaddons
20:12:10.909 T:1961934848 NOTICE: ADDONS: Using repository repository.kodi.game
20:12:10.909 T:1961934848 NOTICE: ADDONS: Using repository repository.libreelec.tv
20:12:10.909 T:1961934848 NOTICE: ADDONS: Using repository repository.zomboided.plugins
20:12:10.909 T:1961934848 NOTICE: ADDONS: Using repository repository.northebridge.by.design.kodi
20:12:10.909 T:1961934848 NOTICE: ADDONS: Using repository repository.tknorris.beta
20:12:10.909 T:1961934848 NOTICE: ADDONS: Using repository repository.Cypherslocker
20:12:10.909 T:1961934848 NOTICE: ADDONS: Using repository repository.xunitytalkWe are not supporting Kodi boxes with several banned repositories installed.
Either present your problem with a clean Kodi setup, or you're on your own.
For now, support stops here.
Sorry, but crystal ball sessions cost extra on our forum.
Because for starters, there is no kodi.log available.