According to Chapter 10, how does a Guru have the power to alter a devotee's destiny?

Chapter 10 of the Shri Sai Satcharitra explains that the Guru is the "one eternal God" and that by placing complete faith in His feet, a devotee can experience profound changes in their life. The text poetically states that the Guru "strikes a nail over the lines of destiny," which is interpreted as changing one's fate. This power is attributed to the Guru's divine status, and the chapter emphasizes that this path of devotion is the best of all means (Sadhana) for untying the knot of birth and death, requiring only faith and remembrance.