Succesfully recovered based on the procedures described at
OpenWRT TP-Link TL-WR941ND.
VCC 3.3V was unecessary; just solder TX to RX, RX to TX, and GND
Before you can use the serial port you have to bridge R356
The device uses TTL @ 3.3V and not a standard RS-232, so do not try to connect it to a common serial port
In my case, portaPuTTY ignored keyboard input; Hyper Terminal worked
Commands used:
setenv serverip 192.168.1.254; setenv ipaddr 192.168.1.1
tftp 0x80800000 factory-to-ddwrt.bin
erase 0xbf020000 +0x3c0000
cp.b 0x80800000 0xbf020000 0x3c0000
reset
I hope that this info could be useful to someone else!
