How could the train accident in Munich happen?

Single-track line between Schäftlarn and Ebenhausen. Ebenhausen is double-tracked, and the Schäftlarn stop is single-tracked. Technical errors have already been ruled out. It couldn't have been the train from Schäftlarn, because it was probably traveling up to the Ebenhausen entry signal. Apparently, that's where the train crossing occurred. Then it can only be the train…