OK, so you can rule out the motors, ESCs, the mixer and probably the receiver. If you unplugged the mixer from channel 1 on the receiver, do you get any control of the motors, or nothing at all? If there is absolutely no response, I would suspect the steering channel is faulty.

That radio is more programmable than it looks. If you go to the product page and click on the files tab, there is a configuration program and dozens of instructions to download. You also need a cheap USB cable that plugs in the trainer port on the back of the transmitter. I haven't tried it, but I believe that you can program the radio to do mixing and eliminate the v-tail mixer - perhaps somebody can confirm that? You may find via the software that your issue is just a badly configured radio, otherwise its time to get in contact with Hobbyking.