Hey guys, it's me again. This time I might have some good news to provide!
Since the startup issue was really affecting me more than I wanted (it was getting stressfull to bend under my desk every day or so, wait a few seconds for the LEDs to be cut off and then press the switch again), I kept looking online for possible solutions, since the issue in my case seemed to be a bit random and not specifically hardware (like I said in my previous post, it got worse after the recent Windows Updates). I found the LinusTechTips site and people there were also discussing this exact same problem with the Dark Hero, which means literally the majority of customers with this Motherboard are experiencing the same nightmare. Somewhere in the comments, someone mentioned they managed to get rid of the issue by activating the ErP (S4+S5) option in BIOS. Since this is something I haven't tried already, I gave it a shot and I'm one of those people who gets extremely anxious and intimidated whenever the BIOS screen shows up... 😄
Guys, let me tell you, for now it seems like the startup problem is solved. I can't say if this is going to be a permanent solution, but the PC booted fine from the power button for 4 days in a row already. The ErP essentially turns off ALL the power from your machine, which means USBs, external devices and also Motherboard LEDs (including the Start button) will be completely off. Personally speaking, I don't really need the LEDs on while I sleep, nor I use the USB ports to charge my stuff. If the MB LEDs are turned off, the power button is supposed to work. If the LEDs and the Start button are on, the Dark Hero glitches out and fails to read the input of the power button, until the power is reset via PSU. This is still unacceptable considering how much this component costs (and my PC is brand new too, already RMAd it once for faulty RAM. I couldn't stand the thought of doing it again for the MB since the shop's policy states I have to deliver the entire PC there and leave it for who knows how long until they're done with the replacement and testing), a similar issue should not occur. Still, since the nice RGB lights are useless at night for me, I was more than willing to give them up on shutdown.
Before opening a RMA ticket or replacing the MB with a different brand at your cost, I would suggest to try this if you haven't already, especially if your system works fine the entire time the system is running.
Note: I do not use Sleep mode and haven't tested it with Hibernate yet, so I can only confirm this works with normal shutdown.