Basically its almost impossible to design a battery to withstand near absolute zero for this period of time (half a month). Nothing is 100%, i.e there is likely some high confidence interval that the batteries and capacitors etc involved could not survive this (found out during cold freeze research and testing etc) but there is some finite small chance worth checking for anyway just in case.
There was no RTG etc like say found on voyager space probes (to provide a steady residual minimum temperature to critical payloads), likely the mass and other budgets would cascade by that and was deemed not worth it.
i.e the thermal management was never designed by its basis to survive the lunar night (and the mission was timed to make full use of the lunar day before it with this in mind tool).
