Why does my 3ds xl do this random draining even with the charger

This started yesterday when I started playing pokemon rangers on my 3ds xl, it just dies at random times well first it is fine for like five seconds and then it starts to drain and then blinks red like when it's on its last battery life. It turns to a dark screen with the blue light at the bottom for charge is still there and then turns off a few seconds later no popping sound at all. It's kinda weird because my sisters 3ds xl has been through stuff like mine a couple accidental drops with the protective cases nerf. Hers never did this and I've looked around asking about it and nobody knows and they tell me to get a new one. The battery is ok because I checked it and it still works for even my sisters 3ds xl, the sd card trick didnt work, and the cleaning the whole 3ds xl didnt work either and I also did the battery reset still didnt work. I'm at a loss here and it would be great if someone could help me because 3ds xls are expensive.