Been trying to solve this issue on my unpatched Switch running Atmosphere 1.6.2 and fw 16.1.0. Using a 1TB SanDisk microsd card, fat32 formatted with hidden Emunand partition. Been doing fw updates up to fw 16.1.0 without any issues but when i tried updating to fw 17.00 and rebooting after...
I may try the new ram site, and download more RAM to my Switch. Not sure if ddr3 is the right ram
for it tho. Edit- no it uses floppy Ram, just like @AncientBoi