Forgot to respond to my previous comment. I bought a replacement Wifi card, and it came in the mail a few days later. Opened up the 3DS again, pulled out the old card, put in the new, and WAMMO, wireless functions worked again. Thanks iFixit!
For those facing a black screen on startup (after having cleaned pins on cartridges and cartridge slot) WITH power light coming on, turn off console, remove power, and try shorting out the capacitor leads. My SNES stopped working suddenly after a single power cycle, and shorting out the leads (while UNPOWERED) revived it.
For those facing a black screen on startup (after having cleaned pins on cartridges and cartridge slot) WITH power light coming on, turn off console, remove power, and try shorting out the capacitor leads. My SNES stopped working suddenly after a single power cycle, and shorting out the leads (while UNPOWERED) revived it.