The word buddha basically means "perfectly mature mind". Mature being. Fully grown up. It's a title like that. So being a buddha means you are fully mature. That's it. Asians don't own it. Buddhism as a religion does not own it. Humanity owns it. Esoteric Christians look within and see the mature spiritual being they will become by practicing the Word of Christ, a mature spiritual being. Esoteric Buddhists look within and see the mature spiritual being they become by practicing the words of a different mature spiritual being. That is my view. Everything else is dickwaving.
First you die in an external way. That is the shamanic death experience. Then, a very few go further and die in an internal way. There are methods for this that are called secret. I have never seen them completely in any book that I remember, not even the Tibetan books that you must have permission to own and read. That is part of the oral transmission. Only those who are meant to experience it will. Christians say those beings have the Grace of God that others do not have. Easterners say karma decides. Same thing, as far as how it is experienced. If you have not watched those Tibetan Book of the Dead Videos you are possibly missing something very important.