Why did Sai Baba appear in a physical form in Shirdi, and where did his presence go after he left his body?

According to the provided passages, Sai Baba appeared in a physical form in Shirdi specifically 'for the sake of the devotees’ protection,' drawn there by their collective past merits and devotion. His purpose was to complete a 'task for the devotees.' After this task was over, he did not cease to exist but rather transitioned. Chapter 43 explains that he 'merged himself into the unmanifest' and simultaneously 'stayed in the hearts of the devotees.' In his true form, he now 'fills the moving and non-moving world,' meaning his presence became omnipresent instead of being confined to a physical body in Shirdi.