I have a WL-500g in my hands which after a failed firmware upgrade failed to respond.

Please note that it isn't any of the newer, fancier models - just a plain 500g.

The situation now is as follows:
The router is always in recovery mode, although it responds to pings. I.e. when one turns it on, the power led starts blinking. It doesn't come out of the cycle.

So, by now I have tried everything:
tftp always times out. Tried to start a normal ftp session, but it cannot login (times out). Tried the pin 10+12 trick. Even tried grounding pin 9, removed the wifi card and replaced it again (as suggested by another user in this forum), but nothing changed.
Everything is unchanged. Always stuck in recovery mode.

Asus utility can't detect it.

I can however always ping it. It responds to all ping requests.
Windows can detect it as a switch and it can see its mac address.

Long story short: I can ping but not upload a file through tftp. Can anyone please help me? I'm out of ideas.

cheers