Factory reset of "unresponsive" device

Long ago I bought a Wt1520 device to play with. But I messed wit the configuration and forgot it for a long time. Now I would like to recover it, but I don't know how to access it. I tried wired connection but no dhcp and usual static IPs don't work. Is there any "reset button" combo to restore initial configuration? And how could I access to it then?




This sounds good, so the way is try to get failsafe mode, and then using telnet/ssh make a factory reset.
I will try when I arrive home.
Does "tcpdump -Ani eth0 port 4919 and udp" always show the message "Please press button now to enter failsafe"? If I remember correctly there should be a openwrt 15.05 installed in the device.

To be honest, I've never had success using that method (I would monitor the interface using Wireguard); and more embarrassingly, I learned what the tcpdump command performs just earlier this year.

I usually do a continuous ping on until I receive a reply.

Nothing on Wireshark, maybe the device is completely bricked. And my soldering skills aren't enough to connect a serial. Time to retire the device :cry: