Not starting with new (4 months) battery.

Hi everyone! This morning my 3 2020 wouldn’t start, no lights, key-fob not even unlocking the doors. This battery is new from August 2024. When I changed it, we ran tests and concluded that there was no phantom drainage and the battery was due for a change, OEM going on 5 years. Now, some people have mentioned that my headlights turn on randomly when the car is off. Wondering if it could be the cause of all this. I always turn the lights off since I don’t have the auto mode. I do have a usb cable plugged that I don’t remove. (For apple car play) Could this be the issue? I’m annoyed cause I’m a car noob and not sure what are the next steps. I’m going to boost it with my booster pack now but what would be the right thing to do after?

Hi everyone! This morning my 3 2020 wouldn’t start, no lights, key-fob not even unlocking the doors. This battery is new from August 2024. When I changed it, we ran tests and concluded that there was no phantom drainage and the battery was due for a change, OEM going on 5 years. Now, some people have mentioned that my headlights turn on randomly when the car is off. Wondering if it could be the cause of all this. I always turn the lights off since I don’t have the auto mode. I do have a usb cable plugged that I don’t remove. (For apple car play) Could this be the issue? I’m annoyed cause I’m a car noob and not sure what are the next steps. I’m going to boost it with my booster pack now but what would be the right thing to do after?