New car dead battery

Yes you posted here instead of calling the dealer where you bought the car. Have you tried reading the owners manual you got with the car? The owners manual may say something about this type of problem (how to avoid it) .

I have the same problem, car sat in our driveway for maybe a week! Completely dead, tried to jump it as well and nothing. It won’t even unlock with the buttons on the key, only manually with the actual key. Calling the dealership tomorrow.

Same problem here. After a two week vacation in our other car I found the battery of my new 2020 Outback dead. I jump-started the car, drove to the dealer and they did not find anything wrong, and they fully charged the battery. The tech said that there is enough active electronics in the car to drain the battery over time. Apparently, a trickle charger is the best way to ensure that the battery stays healthy when the car won't be used for a while..

Subaru factory batteries are crap. Get a high capacity battery like Optima or Odyssey.

3.21 21 This morning is the 4th time the car would not start in the last 10 months. It is always perfectly fine the day before, and had not been sitting, other than overnight. On each occasion the battery was dead, but fine with a jump start. It has been to our dealer at least 3 times before today. The last time in January 2021 they had the car for 8 days. They have never found a cause. They did replace the battery once. I am scared to use the car - do not want to be stuck again

https://www.cashcarsbuyer.com/subaru-battery-problems/

Here's a suggestion for you if you're going to stop driving your car for 6 weeks. Consider having a battery disconnect switch installed after you replace the battery . AAA Battery Service is excellent, they come to your location and if you need roadside assistance and you have a dead battery , they will replace it if dies under warranty . The battery service is good throughout the USA and Canada . Very convenient .

The problem isn’t that the car sat too long, it’s a problem with Subaru. There is a current class action suit against Subaru. I have a 2021 outback XT touring, 989 miles, that goes dead over night. I also have a 2020 outback XT touring that sometimes sits over several months in my hanger while out of town. To date it always starts.