@knoni12 check your charger with a multimeter make sure that it works properly. After that check to see if it charges the battery. Measure at the battery connector to see if you get power there when you plug your charger into the 2DS. If you do not, it is possible that you have a bad charging port. this model is known for bad solder connections on the port or a bad fuse (Fuse F1 located right next to the port is the charging fuse) on the motherboard. You will have to try and remove those screws. They are not glued by factory unless somebody glued them in after. What you need is a good Philips screwdriver and some force to remove those. Make sure that the screwdriver is fitting well otherwise you may strip the screw head.
Check continuity on the fuse with a multimeter and if it fails please replace it, do not use a jumper or similar since that is a recipe for your 2DS to die if anything happens. Any of [https://www.mouser.com/c/circuit-protection/fuses/surface-mount-fuses/|these fuses] will work.