The OP is terribly confused.

"What happens to our consciousness when we die?"

The question makes no sense. The irreversible disruption of metabolic chemistry that for reasons of convenience we all call death implies also the irreversible destruction of consciousness. Asking what happens to consciousness when we die is like asking what happens to a bird flying formation when they land.

[N]euronal firing [only represents] the preconditions that seem to produce consciousness that can/do communicate/demonstrate its consciousness to us.

Any other factors would be irrelevant. With no self-awareness, there's no consciousness worth speaking of.

In short: Physical destruction of the brain entails destruction of consciousness because your consciousness resides entirely and solely in your brain. If the brain tissue gets too damaged (most commonly from lack of oxygen), it dies, and you with it. There is not, and cannot be, any afterlife.