We have had a bricked Vigor130, which would not reset. We were unable to reach it even after resetting multiple times.
It was pingable on 192.168.1.1, but did not reply to any open ports with nmap scans, nor did it act as a dhcp server.
We connected a TTL adapter to the 4 pins on the board to see if there's a serial console on it.
| +3.3v | RX | TX | GND |