Topic: Need help with my old 3DS XL

Hello, first of all im not very good in English so I will try my best to express what is happening. I couldn't find answers anywhere (here or on google) and I'm still waiting for Nintendo Support response for about 1 week now.

The problem: I have an outdated 3DS that I was not playing anymore for some years now, but i got a lot of new games recently and got back playing it. Mostly of the games need an update to play online though, so thats where my problem starts. Everytime I go to "System Settings" to configure my new Wi-fi, the 3DS freezes when i hit "save" and thats all. If I try to delete a previous Wi-Fi connection, the same happens as well.The music continues, but the screen just stops working.

Here is a video showing what it happening: https://www.youtube.com/watch?v=6T38ElXNDg0

1 - I can't factory reset/reformat or update it because i need a working wi-fi connection to do that (that i can't configure). So even if i try to use L+R+A+UP to update, it does not work.

2 - I already tried to change settings for a previously existing wi-fi, but the problem happens as well.

3 - I tried to leave the 3DS on for some hours after I hit "save", but nothing happens.

4 - There is no physical problem on the 3DS, no hits or liquid damage.

5 - I do not have access to old Wi-Fi connections since i moved cities for some years now.

Any suggestions?Thanks for your patience and for reading till here.