_{If the user, Illogical Consistency (who suggested the edit) posts their own answer, then this wiki answer can be deleted}

From this (rejected) suggested edit:

I had to dig deep into several other websites and found out that I had to partition my newer 32gb usb with a FAT32 4096 partition and only put the .SH4 .CBD and .TXT files in the root. On then would the firmware update properly.

From this comment:

I dug deep into several other websites and found out that I had to partition my newer 32gb usb with a FAT32 4096 partition and only put the .SH4 .CBD and .TXT files in the root. Then the firmware finally updated