Xiaomi Mi Router 4A Gigabit Edition (R4AG/R4A Gigabit) -- fully supported and flashable with OpenWRTInvasion

Hello everybody,
I am very new to this. So, I managed to brick my new Xiaomi 4A 100m Router.
Now I am stuck at debricking it again. All attempts to flash the newest manufacture firmware 2.18.58 not succeeded.


That is what I observed so far:

At the beginning the left LED is flashing yellow about a minute, then switches to blue and keep flashing blue all the time.
Tiny PXE Server stays at this state:
Screenshot (49)

I get no access through 192.168.31.1 or router.miwifi.com.
No basic gateway is listed in details of the LAN port. Yes, I always switch back afterwards to obtain ip automatically.
Alter I unplug the power connection for a short time the left LED is yellow again and I still can’t access the router.
After restart the LAN-connection to my pc is cutted. To restore it I need to push and hold the reset button.


Should I try to flash a firmware below 2.18.58? Make that sense to you? Could then somebody please provide me an older firmware?

Is @hoddy’s guide still a good way to go? Or should I try another guide?
What else can I try to debrick my Xiaomi Router?

Thank you so much for all this here. I hope someone can help me.