According to the source, what specific austerities or practices did Sai Baba perform to attain Lord Vishnu?

While Chapter 36 of the Shri Sai Satcharitra makes the statement that Sai Baba, 'having renounced worldly life, he who attained Lord Vishnu (Chakrapani) has redeemed infinite beings,' the provided excerpts do not describe the specific austerities, penances, or practices he undertook to achieve this union. The focus of this section is on his qualities and actions after this attainment, describing him as a 'complete supporter of spiritual goals' and the 'incarnation of the knowledge of Truth.' The text emphasizes the greatness of saints is infinite and cannot be fully described, rather than providing a biographical account of his spiritual practices.