Hacking [Guide] Downgrade from 5.5.2 to 5.5.1

[ghettosuperstar]

I was a fool not to re-enable my router blocks for the NUS sites and my Wii U 32gb got upgraded. Was about to buy another Wii U when it dawned on me that I still had a backup of my MLC (emmc) and my SLC (nand) on my SD card and on my PC.
So as of right now, and few bottles of rum later, I am back on 5.5.1. My guide will be simple because I will just point you to the relevant stuff that's needed to pull this off. Thanks to @Kafluke and @Leeful @EyeKey @dimok789 @koolkdev for their guides and tools.
Note: This is not for the faint hearted. You will be doing micro miniature soldering and you need a solder iron with a very tiny tip.

• Weller Long Conical Tip, 0.4 MM, 800° F http://www.frys.com/product/1486203?
• Another tip (no pun intended), always use fresh solder. After every use, clean your soldering iron tip and apply new solder. This makes soldering so much faster and you only have to hold the soldering on that spot for less than a second.

WHAT YOU'LL NEED

Spoiler: Pre Setup

You need some type of backup from one of the following:

• Rednand on SD card or
  
• Wii U Nand Dump or
• Backup of otp.bin, slc.bin, mlc.bin

I DON'T HAVE otp.bin!

Spoiler: Otp.bin

If you have rednand and way back you only got the three files (slccmpt.full.img, mlc.full.img, and slc.full.img) and you never did anything with the SD card you extracted the nand images from, guess what you in luck.
Use sdio nand manager to get the otp.bin from the SD card. While you at it, dump all 5 images under nand manager at least three times and then do a HxD comparison of the files to make sure you don't have errors during the extraction.

1. dimok789/sdio nand manager https://github.com/dimok789/sdio_nand_manager/releases
2. HxD - Freeware Hex Editor and Disk Editor https://mh-nexus.de/en/hxd/

Fix you nand using Eyeful tools.

Spoiler: SLC nand wrong size.

1. Use EyeKey Wii U NAND Tools https://gbatemp.net/threads/release-wii-u-nand-tools.465386/
2. nandFixer.exe <input rednand dump> <output dump> adds missing information to your nand
3. nandBinCheck.exe <path to dump> <options> checks that your nand has everything and has no errors. Once you get no errors then you the use the slc.full.img or slc.bin file for the below.

Soldering and Restoring
*****NOTE: You can't restore just one or the other. If you restore just the nand, you will still see that you are software version 5.5.2. If you restore just the eMMC, you will get brick screen or Error code 160-0103.
You must restore both slc.bin (slc.full.img) and mlc.full.img to get back to 5.5.1. I spent a whole week troubleshooting to tell you this.

Spoiler: Teensy for the Nand

Follow

1. Kafluke's HardMod CBHC Unbrick guide https://gbatemp.net/threads/guide-kaflukes-hardmod-cbhc-unbrick-guide.476725/
2. You will flash slc.full.img or slc.bin to the nand
3. And this will take 3 hours to flash.

Spoiler: SD Card and Reader for you eMMC nand

1. Leeful "Successfully dumped WiiU EMMC nand with hardmod." Guide https://gbatemp.net/threads/successfully-dumped-wiiu-emmc-nand-with-hardmod.457165/
2. Win32diskimage https://sourceforge.net/projects/win32diskimager/
3. Depending how good your soldering is, restoring from the sd card reader can take up to 2 hours or as quick as 30 minutes.
4. @Kafluke mentioned that he didn't have to cut the CLK trace. So before you cut the trace, try reading the eMMC image 2 or 3 times and compare using HxD. You may get lucky if your SD card reader has a stronger clock signal. For me I had to cut the clock trace and create a jumper. Tried it without doin it. Didn't work.

I can confirm all entry points still work after downgrading and I am spending the $6.99 to buy Brain Age to install Haxchi after finishing this guide.
***Note:
Just finished downgrading. I paid my $7 bucks for Brain Age. Couldn't get it to finish. If you click on Download Management, you will see the update to 5.5.2 (it won't say this but you can just assume) with a X, because you most likely have it blocked via DNS. Just click on the update and you will be presented with a option to delete content. (I don't remember actually what it said.) Delete and your ds game will download and install.
Tip from @Jhynjhiruu: check eshop to see if you got Brain Training for free. He created a account and it just showed up.


Pour me a drink!!!

 

[Deleted-355425]

For the people who wish to future proof, whats the best way to get a your nand dump, otp.bin, slc.bin and mlc.bin while on 5.5.1?

 

[ihaveahax]

For the people who wish to future proof, whats the best way to get a your nand dump, otp.bin, slc.bin and mlc.bin while on 5.5.1?

https://gbatemp.net/threads/nand-dumper-create-full-dumps-of-the-nand.465680/
https://github.com/koolkdev/wiiu-nanddumper/releases

 

[ghettosuperstar]

thank you ihaveamac

 

[Kafluke]

Great job @ghettosuperstar! I was too afraid to try. Chalk up another success to captain morgan!

@EyeKey and @Leeful what do you guys know about cutting the trace? OP says he had to cut the trace bit I didn't have to cut it during the unbrick guide. Thoughts?

 

[ghettosuperstar]

I think the clk signal trace has to do with which signal is stronger, the one from the Wii U or the one from the SD card Reader. My SD card reader is one of those small usb plugin with a slot for micro sd or Full size SD. With the SD specification, you typically have two clks that is a negotiated signal 0 to 25mhz (one internal in the memory, and one external usually on the connecting device). Now imagine when you stick a third device tryin to negotiate the signal speed. I will change the guide to reflect not cutting the CLK trace first.

 

[JinSaotome03]

Hello! I'm new with all of this so I would like to ask for help.

So, I just bought a Wii U console a couple of days and trying to hack it the damned console just updated. With his method... do I need a hardmode to downgrade or something? (you know, like opening the console and weld some wires and that). I would like to give it a try but I don't fully understand what's the process so I want to be sure before trying anything.

 

[Kafluke]

Hello! I'm new with all of this so I would like to ask for help.

So, I just bought a Wii U console a couple of days and trying to hack it the damned console just updated. With his method... do I need a hardmode to downgrade or something? (you know, like opening the console and weld some wires and that). I would like to give it a try but I don't fully understand what's the process so I want to be sure before trying anything.

You can't do anything to downgrade unless you backed up your sysnand and yes, you'd have to tear your Wii U apart and do some micrisoldering. Not for noobs

 

[Leeful]

@EyeKey and @Leeful what do you guys know about cutting the trace? OP says he had to cut the trace bit I didn't have to cut it during the unbrick guide. Thoughts?

Cutting the trace is just for the EMMC chip (mlc) part. You did'nt have to cut the trace doing the unbrick guide because that is just using the TSOP chip (WiiU nand).

 

[Kafluke]

Cutting the trace is just for the EMMC chip (mlc) part. You did'nt have to cut the trace doing the unbrick guide because that is just using the TSOP chip (WiiU nand).

Aaahh. That makes sense

 

[asper]

With full access to IOSU I suppose this can be also done via homebrew (just like with wii) but bad readings form SD can be a real nightmare...

 

[ghettosuperstar]

My nightmare (cause to drink more rum than needed) was inconsistent dumps from the nand and emmc. I usually dump first (at least 3 times) so i have something to go back too.

 

[Sonic Angel Knight]

I'm glad there is ways to downgrade but I'm not really qualified for soldering, so I really feel like is not as helpful to me, no offense to anyone with guides revolving around it.

So Cheers to you on restoring your system. Hopefully we won't need to downgrade anymore but to just fix problems. (and maybe not need any expert engineering)

 

[MattKimura]

That whole thing about deleting the failed update in Download Management is pure bull! There's no delete button, just view details about the error.
The solution is to unplug the system from the back. I don't know of any other methods of removing the failed update, but this was proven to work.

 

[AmandaRose]

That whole thing about deleting the failed update in Download Management is pure bull! There's no delete button, just view details about the error.
The solution is to unplug the system from the back. I don't know of any other methods of removing the failed update, but this was proven to work.

Thats exactly what I was just about to post lol but you beat me to it. Plus for the last time can people please stop claiming brain age is free it is not. It was only free for people in europe who created a nnid before July 2014. Why on earth would nintendo be so dumb to make it free now knowing full well people would just download it for haxchi. Nintendo is dumb just not that dumb lol. And to prove the point I just created a new nnid and accessed the eshop and shock horror brain age is still £6.29

 

[Flypop]

First of all I want to congratulate all of you for this success. Now, my nephew connected my Wii U to internet and updated to 5.5.2 and I don't have NAND backup, otp.bin, slc.bin, mlc.bin, nor nothing. So the question is: Can I dump my 5.5.2 NAND via Hardmod, substract otp.bin, slc.bin, mlc.bin from it and inject it to a donnor 5.5.1 NAND Dump in order to downgrade? Is it possible? Or I am screwed beyond any possibility?

 

[Kafluke]

First of all I want to congratulate all of you for this success. Now, my nephew connected my Wii U to internet and updated to 5.5.2 and I don't have NAND backup, otp.bin, slc.bin, mlc.bin, nor nothing. So the question is: Can I dump my 5.5.2 NAND via Hardmod, substract otp.bin, slc.bin, mlc.bin from it and inject it to a donnor 5.5.1 NAND Dump in order to downgrade? Is it possible? Or I am screwed beyond any possibility?

If you dont have HaxChi you cant do anything. If you dont have the files needed previously dumped while on 5.5.1 you can't use a hard mod to get them.

Yes, if you're on 5.5.2 and you don't have HaxChi then you're boned

 

[Flypop]

Oh well!!! Sometimes you're on top, and sometimes you're nintendo's beef. It can't be helped, sighs. Thanks a bunch anyway.

 

[jbuck1975]

Oh well!!! Sometimes you're on top, and sometimes you're nintendo's beef. It can't be helped, sighs. Thanks a bunch anyway.

Be patient. Something will come along

 

[RandomUser]

For the people who wish to future proof, whats the best way to get a your nand dump, otp.bin, slc.bin and mlc.bin while on 5.5.1?

Also you can delete the "update" folder off your sysnand, then no more possible system update it seems.