Chrysler Pacifica 2018 having problems to start

My 2018 (18K miles/ 1.5 years old ) Pacifica was having problems to start. First day Needed to press push to start button a second time for it to crank and be able to start, but was able to use it the whole day following same approach. Next morning it was not starting at all, it had to be towed by Chrysler Roadside Assistant provider and taken to a Chrysler service place. Two different providers try to jump start and it didn’t work. Battery and charging system tested good at service place. The problem was the secondary (smaller) start/stop battery having a bad cell. It was hard to identify by service tech because main and secondary battery are connected together so needed to disconnect the smaller one to be able to find it was defective. All service labor and part were covered by basic 3 yr/ 36K miles warranty.