Just FYI. Seemingly permabricked my N3DS, here's the details.
Started w/ 9.4 US Majora's Mask. Browserhack *check* > Verify 10.3U files *check* > Upgrade went smoothly *check* > reboot into permanent black screen *check*. I've tried booting into recovery, nothing works. GG.
Also, I used SULib.