A worker dismantles at Twitter's sign at Twitter's corporate headquarters building in San Francisco
James Musk was discovered in an office soundproof phone booth, author Ben Mezrich said.
  • An ex-Twitter exec once found Elon Musk's cousin James Musk "basically sobbing," Ben Mezrich said.
  • The author of "Breaking Twitter" said James Musk had been worried about being fired.
  • James Musk was brought into Twitter after Elon Musk paid $44 billion for the company.

Elon Musk's cousin James Musk was once found on the verge of tears in Twitter's San Francisco headquarters, the author of the new book "Breaking Twitter" said.