Hello Igor!
Thank you for your answer! Sorry, that I am responding so late - I have not got a notification... and just wanted to check up on the topic a last time..
As I saw you answered I took out the sd card and reflashed it with the image you were linking to. I tried to flash it 3 times but did not get it up and running:
The first try I use win32diskimager and had an usb wifi dongle and usb keyboard receiver connected to the board via an unpowered hub. It took about 3 minutes before I was getting constant errors - I removed the hub, restarted, tried with the wifi dongle directly - failed again.
Flashed the same way, removed the dongle and failed again. (Not documented here) Reflashed the image again with etcher, started without anythingn than an hdmi and the power cable hooked up - failed again (try2).
So lastly I wanted to make sure that the ayufan image still works - reflashed - system came up in about 30 seconds.
As I was afraid that it would go that way I thought I make some pictures throughout the process.. sorry that they are not the best. If you have any further ideas what the problem could be, I still can try it out this or next week before I move the board back to the housing destination if everything keeps running stable with the ayufan image on the emmc module.