This is an interesting history that was surrounded by mysteries until recently. In Sweden, where I live, it is well known of course. Author Bea Uusma has done intense research many years ago and written a very good book on this expedition, also available in English ("The Expedition: Solving the Mystery of a Polar Tragedy"). In summary, what did go wrong? You guessed correctly: poor planning, poor technology, poor preparations, too optimistic expectations, zero previous knowledge or experience about polar conditions and, at the end depression and hopelessness. Poor little fools that did not realize when to stop while they still had time :-(