While this could be a battery failure, the data look more like the result of a battery that was in auto-discharge resulting in the cells being unbalanced. The initial battery level registered as only 95% and the cell voltages dropped fast under moderate current draw, with cell 1 collapsing as noted earlier by @Meta4. When was this battery charged - i.e. how long before the flight?
In that case it is battery failure. Unfortunately both the aircraft and battery are out of warranty, so the best outcome is probably a discount on a replacement aircraft.