I had the same symptoms as you. Tx/Rx powered up okay, there was video static without the transmitter on, then I turned it on and just got black screen. The camera was warm. It turns out that hobbyking had the wiring incorrect where it attaches to the camera. If you look at the circuit board, it says "+", "-", "vout". They had it wired like this:
Camera Harness
+ vout
- -
vout +
I tried to just swap the pins in the connector, but I ruined them. I ended up just soldering the wires onto the open vias. If you look at the circuit board, there are two sets of these nodes.
After I swapped them, it worked great.
BTW, my cam does not have a speaker like the one pictured earlier in this thread.
Hope this helps someone.