I'm not sure if you're saying if the key won't turn, or that the key turns, but the engine won't start.

In one part you mentioned that the whole dash panel went dead. That's not a typical security feature that I know of. When I was experimenting with ebay key fobs, I found that if the security system doesn't recognize your key (even though it turns), the car will still start, but within a second or two, the security system kills the engine. So the problem you're describing doesn't sound like a security measure. It sounds like an electrical problem.