If you're still reading this thread, IRONRINGED, hex editing anything won't fix bad NAND storage. Software can't make a bad storage cell be a good storage cell. (And UFS isn't SSD, it doesn't really support block switching.)
Thanks. I called Samsung, and my phone was still under warranty. They told me to take it to a repair shop, and the motherboard needed to be replaced. The repair was free, and I've got my phone back working again.