How could you describe exactly the primordial state in which Gautama Buddha was?

Catherine Suraya Prem, Awakening Guide, Spiritual Counsellor.

I think you are confusing The Primordial Buddha with the Buddha Gautama.

The Primordial Buddha is not as belonging to anyone specifically but it is the original, timeless and eternal dimension that can also be called Pure Awareness or Consciousness. It is the Ground of Being and is in essence what is realised upon enlightenment. Buddha Gautama realised this upon enlightenment as the Empty nature of self which is Buddha. But this realisation is not confined to Buddha Gautama, it is the same realisation that all who attain enlightenment realise.

The Primordial Buddha is the self-originating, self-emanating Buddha, who existed eternally before anything else...

 “I am the core of all that exists. I am the seed of all that exists. I am the cause of all that exists. I am the trunk of all that exists. I am the foundation of all that exists. I am the root of existence. I am ‘the core’ because I contain all phenomena. I am ‘the seed’ because I give birth to everything. I am ‘the cause’ because all comes from me. I am ‘the trunk’ because the ramifications of every event sprout from me. I am ‘the foundation’ because all abides in me. I am called ‘the root’ because I am everything” - Samantabhadra Buddha

This comes from the Dzogchen teachings.

Samantabhadra means always good or ultimate goodness which is the ground of our being.

Source:  Quora   12/29/2017