If your player won't boot, the only way to edit the config.ini file now is with a terminal program on the serial port. Instructions for sending and receiving files via serial is here, but make sure that you pay attention to the note in this FAQ entry about manually editing your config file.

By the way, regarding the DHCP address: Usually, your player will get the same IP address every single time, so odds are you just use the same one you used last time and it will work. So you might not have to resort to serial.