Okay, so I'm making this short little thread to explain how you can downgrade back from Evilnat's 4.89 to REBUG D-REX 4.84.2 if you happen to be getting the "Data Corrupted" message via System Update
1. Download
REBUG 4.84.1 REX from the link provided below.
https://archive.midnightchannel.net/SonyPS/Firmware/?cat=rebug
MD5 is 8B68282425665FD4453B8AE14839D876 / File Size is 204.06 MB
2. Format a USB to FAT32 & make a "PS3" folder, then an "UPDATE" folder inside of "PS3" which is where the PUP will go.
Structure should be like so ->
[F:]/PS3/UPDATE/PS3UPDAT.PUP
3. On PS3, make sure your QA Flag is Enabled via REBUG Toolbox or "wherever"
4. Install the PUP to PS3 via System Update using the USB slot closest to power button
5. Once 4.84.1 REX is installed, open Rebug Toolbox, go to "Utilities" and "Dump eid root key"
6. After PS3 restarts, open the Toolbox again and "Rewrite Target ID in Flash"
7. Now your TID should be DEX & LV2 will still be CEX until you install 4.84.2 D-REX via System Update
And once 4.84.2 D-REX is installed, then you can use LV2 swaps to change between CEX/DEX modes.