In the cockpit, the engine fuel mixture control was found pushed in and guarded, and the carb-heat lever was unlatched and pulled halfway out.
The carburettor system features a heat assist function to adjust carburettor heat mechanically as the collective lever is raised or lowered, which is designed to improve safety and reduce pilot workload.
It's not clear to me if carb-heat may have been an issue or not? It certainly wouldn't be the first time.....