I think the same thing happened to you, but I solved the problem by installing Android, after I installed the Android system right away the Nintendo Switch was correctly reading the SD card reader and I could restore it .. Good luck ...
I had the same problem with "Error: NOFAT Failed to mount SD card (FATFS Error 13). Make sure that a FAT partition exists" - Use MiniTool Partitio Wizard Proffesional and format card Primary partition non Logical!
I had the same problem with "Error: NOFAT Failed to mount SD card (FATFS Error 13). Make sure that a FAT partition exists" - Use MiniTool Partitio Wizard Proffesional and format card Primary partition non Logical!