Did Sai Baba's ability to help his devotees end when he left his physical body? What does the text say about his current state?

No, Sai Baba's benevolent nature and ability to help his followers did not cease after he left his body. Chapter 48 explicitly addresses this, stating that by merging with the Unmanifest, his form attained formlessness, but his quality of being a benefactor to devotees did not end. It beautifully explains that the very same actions and experiences of his grace that were performed while he was in the body are still experienced today by those who are devoted to him in his Unmanifest state. This confirms the continuing presence and protective grace of Sai Baba for those who seek refuge in him.