Did Amir Shakkar follow Sai Baba's instructions to stay in the Chavadi perfectly? What happened when he deviated?

No, he did not follow the instructions perfectly. Chapter 22 recounts that after a long stay, Amir grew tired of the confinement, which felt like a prison to him. His mind craved freedom, and a thought arose to leave. Acting on this, he left the Chavadi and went to Kopergaon without Baba's permission. The immediate consequence described is quite dramatic. Upon arriving at a Dharmashala in Kopergaon, he encountered a Fakir on the verge of death from thirst. Amir felt pity and gave him water, but the moment the Fakir drank it, he died, leaving Amir in a startling and precarious situation.