Hello!
Things I have verified:
I received a OLED Switch with installed SX Lite Chip (Burnt Fuses (ODM 7/6): 15 - 0 (HOS: 12.0.2+))
I downloaded the latest HATS Pack, created emuNAND and booted into Atmosphere successfully.
Things that have been told to me (Not verified by me yet!):
SX Light...
I updated the firmware of sx core on the PC, formatted the sd card and put the latest atmosphere on it, disassembled it again, soldered the contacts again, put it back together and everything worked. Apparently it's really a matter of bad soldering.