I haven’t driven my 2019 in sight for about two months. I’ve been checking it every week and main battery seems to be holding its charge. Today it’s totally dead. I had to unlock it manually. I guess the other battery died.I jumpstarted it but it soon as I disconnected the cable diet again. What should I do?

 

Replace the battery.

 

You could also try trickle charging the battery. Unless you drive the car for a couple of hours upon jump starting it, a tiny bit of idling would not charge the battery. Immobilizers and other items draw a little from the battery and without a battery tender, it will kill the battery over a period of a month or two.