3DS black screen (blue light on)

Hello, when I tried to play on my 3DS while it was simply closed (but turned on, not in sleep mode), I was greeted by a black screen.

The blue light is on; if I hold down the power button for a long time, it eventually turns off and I can turn it back on but it still shows a black screen. I can also access the update screen with the L+R+A+Up combination, but that doesn't change much.

I've tried quite a few actions like holding down the power button for a long time, turning it back on without a cartridge or SD card, and trying to plug it in for a while, but still nothing.

I should also mention that my console is about five years old, so it's not really a question of sending it to customer support if I can fix it myself. Especially since it was working perfectly two minutes before the incident; I just suspect a software issue, but I'm not really knowledgeable about it...

Thank you in advance if you have a solution to offer me! I'm honestly frustrated by this sudden breakdown when everything was working fine just yesterday...