I have a idea.
Windows-10 has now changed the way Fast Startup work, no longer is linked to SecureBoot or FastBoot
Disable both secure boot and fast boot in UEFI/Bios . You don' t have to necessarily disable hybernation, unless your S4/S5/S6 Lan wakeups are all connnected, if your new to the terms they are (power states) and windows-10 mess's up so to say when Lan settings end up being ON with certain options causing Win10 to still not do a proper shutdown
Investigate that part also set your PC to Safe Mode minimized bootup before running the following tasks
Disable Hybrid shutdown
Admin CMD Box run these commands as Admin either CMD or Powershell either works fine.
powercfg /h type REDUCED
chkdsk /f
After chkdsk finishes and Win10 is finely set to perform a Real shutdown known , shutdown your PC restart and it should take a really long time to start
If you still think your PC isnt shuting down properly and its still focing fast startup and it still took a long time to start but just cant get rid of the Fast-Stratup Bug run this. Yes it is a known Win10 bug no matter what system is running Win10 everyone is now advised to disable Fast Startup from Fresh installs to reinstalls to Refreshed Installs and MAKE SURE THE LAN SETTINGS ARE GOOD TO GO.
Lan is yet another bug they just cant fix yet ....
Performing a real shut down in Windows COMMAND
Shutdown /s /t 0
Power back on the PC
You should boot directly into safe-mode and check to see if the GPU is now at least showing in device manger.
If it is good, if its showing but with yellow triangles just let me know, i got a work around idea for that. If its showing but disabled , thats a whole other problem but not one that wouldn't be fixed if you check the settings i listed.
You should never see Yellow Triangles anywere mot even in safe mode, that means basic system drivers are missing or if at Normal Boot, Device Drivers have malfunctioned. Depending on whats got the triangles depends on how serious it is, Good idea to list any Yellow Triangles your seeing Including the new HyperV mess Win10 now has going on. FUN FUN 
You say you tried everything but probably never looked into the LaN problems and a ton of other things i dont see you listed, Dont give up its solvable. It wont matter if you have a LaN installed or rip the LaN directly out the PC, Win10 uses its registry and settings regardless of setups, so the problem will persist until we find out what windows10 is seeing and correct it 
Windows 10 Fast Startup could be detrimental to your computer
How to Enable or Disable Fast Startup
Deciding whether to bother with Fast Startup actually takes longer than turning it on or off. First, open up your power options by hitting Windows+X or right-clicking your Start menu and selecting Power Options. In the Power Options window, click “Choose what the power buttons do.”
If this is the first time you’ve messed with these settings, you’ll need click “Change settings that are currently unavailable” to make the Fast Startup option available for configuration.
Scroll to the bottom of the window and you should see “Turn on fast startup (recommended),” along with other shutdown settings. Just use the check box to enable or disable Fast Startup. Save your changes and shut down your system to test it out.
If you don’t see the option at all, it means hibernation is not enabled on your machine. In this case, the only shutdown options you’ll see are Sleep and Lock. The quickest way to enable hibernation is to close the power settings window and then hit Windows+X and open Command Prompt (Admin). At the Command Prompt, type the command:
powercfg /hibernate on
After turning hibernate on, run through the steps again and you should see both the Hibernate and Fast Startup options.
