From A Cricketing View:
1. Praveen Kumar’s reaction suggested that he didn’t wasn’t sure about the 4.
2. Eoin Morgan’s reaction suggests that it was clear to him that the ball was still very much in play.
3. The Umpire did not hand Ishant his sweater until after the stumps were broken. They did not call Tea either.
4. The Umpire did not declare a boundary (this is the clincher in my view)
So nobody other than Bell thought the ball was dead. As such, it was the correct decision to rule him Out. As per the rules the ball is judged to be dead only when both sides appear to accept that it is dead. In this case, Eoin Morgan thought it was still in play – this is the one thing that multiple reports agree on.