D-Link Dir-600 B5E slowly blinking nothing else

I know its an old device for scrapyard, but i would like to make it run as a challenge.

I followed the steps for installing the OWRT here by installing the special version of firmware to be able to access Emergency web interface.
Unfortunatelly I got stucked right there. Firmware has been accepted, there has been page with countdown. I waited, router stayed black.
After sometime I unplugged the power and from that point, there is following behaviour.

  1. reset button is completely ignored - really it does nothing
  2. power LED flashes veery slowly, around one blink per second and half
  3. cannot connect to it via LAN cable, LAN LED is blinking, like its communicating somehow, but by pinging it I got either "timeouts" or "host unreachable". Interesting is, that there is no pattern. some packets are lost, some denied.

I use WIN10 and if my eyes are correct I use straight cable.

1)Do you think, that only way now is to solder the serial interface according to the manuals on the forum?
2) Is there any point in trying to use crossed cable?

Thank for any advice

Probably helps - and the serial console will already help you determining what has happened to the device in the first place. However, a fiver for the serial console, around 20+ for basic soldering equipment are probably not economically viable for the device in question.

No, you dont need to solder anything. This router is based on RealTek chipset, is mostly impossible to write the boot sector of this chipset, just do a 30/30/30 reset so the router goes to emergency boot screen back again. Also remember that emergency boot is through the WAN port, not the LANs.
By the way, I have run 19.07 ver. on this router but ends up with amnesia this is because the image of the firmware uses almost the entire memory of the flash chip, unless your willing to sacrifice parts of 19.07 to make it smaller, I would suggest you to use version 17.
Also, this router as you may know its pretty much old and its CPU is solw, so it takes a lot of time to load the firmware (mine its about 2-3 min.)