Updated from Hekate 5.1.1 to 5.1.2 and 9.4+15.2 of Atmosphere+Kosmos to 10.4+15.3 respectively. Used the sdsetup site to do so. Updated system firmware with choidujour from 9.0.1 to 9.2 on sysnand cfw.
Booting into sysnand cfw works, but getting black screen after initial Kosmos->Atmosphere...