I also recommend both the Begin Again book and the Kyle Gann one. They are really good complementary texts. Begin Again is a very straightforward biography, simply writing about the man as one would any significant figure in history. The Kyle Gann one is the opposite, yet still very readable, digging into his music and philosophy.
I reviewed Begin Again for the magazine Nature when it was first published. You can read here:
https://www.nature.com/articles/469296a