I've managed finally to fix the phone, but solution is not simple. It involves disassembling the phone,
and possibly some soldering of one IC and capacitors
You have to open a phone, and there is a white, 4-pin connector which looks similar to small audio connectors on sound cards.
It has following pinouts: 1-Vcc 2-GND 3-Rx 4-Tx.
Unfortunately, you can not connect this to you PC COM port directly, converter is needed.
You can buy one or build it yourself, nice instructions can be found here:
Once you have everything in order, open you favorite terminal program (Hyper Terminal or similar) and setup you serial port to 115200 N 8 1.
Restart the phone. Lot of information will be shown on your display. At some point, it will display an error and stop. I did not capture this information while I could, so I can not give a details. Restart the phone again. You will see a message to press CTRL-I within 3 seconds. After you do so, regular boot will stop and some basic shell will display. To get the list of available commands, type “help”.
We need 2 commands: “net set” to configure IP address to match your LAN and tftp to transfer and flash the newest firmware.
You will need to setup tftp server on your Pc or laptop. Freeware tftpd32 or similar.
Type ‘net set’ and it will prompt you for IP, subnet and gateway.
Now try to ping your phone from PC. If everything is fine, place the firmware (v2030SG.R11.1.090305.2.67.2.zz) into root of your tftp server.
On phone, type:
tftp <ip_address> v2030SG.R11.1.090305.2.67.2.zz
where ip_address is IP of your PC where tftp server resides.
If everything is setup OK, the file will be transferred and unit flashed.
Phone managed to boot after that, all I had to do is factory reset from phone interface.
After that, you can use WEB browser to configure, admin password is 784518.