The more diagnostics you do now, the less time with support. If you have an external monitor, connect it. If it displays, then your issue is the LCD. If it does not, it probably is something on the motherboard.
For me, I never call Dell. I pull up a chat window and work it that way. Usually within 5 minutes I have the call logged and service on the way.
Funny, I am waiting at home now for the Dell Tech. Motherboard #3 going in this afternoon (sent from my wife's Compaq).
I tried to connect an external monitor (HP1907) that i use with my external display... but still nothing.
I tried the chat window but they wont let me in with my service tag, and try to make me phone them.