(2/2) just boot into Luma, check system info, (like the system version, battery, etc,.) test the hardware, (buttons, sound, possibly 3D?) or use different recovery tools, or just boot (or, at least have instructions on how to reboot) into the 3DS's built-in recovery, which just downloads the latest system updates, and re-installs system apps if missing.
(man, that's a lot of or's...)
Jayro Jones.