"Until two old batteries lit up"
Drawing your attention to post 395:
The auxiliary power unit battery, manufactured by GS Yuasa, was the original battery delivered with the airplane on December 20, 2012. It is comprised of eight individual cells. All eight cells came from the same manufacturing lot in July 2012. The battery was assembled in September 2012 and installed on the aircraft on October 15, 2012. It was first charged on October 19, 2012.
6 months after build and less than 3 weeks in revenue service is not an "old" battery.