Hello,
I have a New 3DS (non-XL) that randomly stopped working a few years ago. I tried many things at the time, and intermittently tried to fix it over and over again.
Currently it turns on to the blue light, screens are always black.
Here's what it can do, with and without SD card inserted...
i gotta say, the steam deck isn't a bad deal, even if you get a used one, you have options to get it serviced and the parts are also available through ifixit