DND, Headset, Mute and Speaker lights on. Why does it appear to be dead?

Your phone is probably broken. I have the LG IP8830 witch is a similar model and I'm using it with the SIP firmware. I have never seen my phones come up with a blank screen. You can try re-loading the firmware if you have it. You will also need a TFTP server setup. You can run TFTPD32 on a Windows PC as your tftp server. The following are the steps for re-installing the firmware on the IP8830.

Phone lock-up maybe caused by an error in transport during the
software upgrade. To correct this problem:
1. Disconnect power from the IP Phone.
2. Press and hold the [Up] and 2 button while reapplying
power.
3. Release the buttons when the Message LED extinguishes.
4. When the BootC screen appears, enter the digits 1, 2, 3
and 4.
5. Follow the prompts to configure IP parameters for the IP
Phone.
6. At the "Server Addr?" prompt, enter the TFTP server
address where the IP Phone can find the BootC firmware.
If already correct, press the [Next] button.
7. At the "Do you want to apply default?" prompt select the
[Yes] softkey to use default or [No] softkey to use
previously assigned parameters.
The IP Phone will reboot and return to normal operation.

Hope this helps