If your IP phones is dead, you can try to update the firmware through post mode.
The detailed steps are:
1. After you connect your PC with the wan port of the IP phones, please change local IP of your PC as 192.168.10.2/255.255.255.0, just like this:
2. please open the FTP server in your PC, here we take home ftp server as example, and make the username and password as root/root, and put the firmware of the IP phones in the folder path of ftp server, at last please click the button of start server.
3. please power off your IP phones, and when you power on it, please press # on the phone immediately, and you will see the words post mode on the screen of the phone, at th same time, you need to input telnet 192.168.10.1 within 5 seconds in your PC.
you will see the following screen:
4. please input 3 to clear all the previous settings, and then press 2 to update the firmware.
192.168.10.2 is the local IP address of your PC, 1.z is the firmware file, root/root is the username/password of ftp server.
if the update is successful, you will see the following screen:
after that, please input 4 to reboot the IP phones.
If the ip phone still is dead after you update it, you can try to restore the factory settings in post mode.
when you see the words post mode on the screen of the phone, you can press *#168 on the phone, and then power off it, the phone will be restored the factory settings.