[Honor 4C Guides, News, & Discussion] hackslash:
It's a pretty straightforward guide. Just follow the guide carefully and you'll be in no time rocking with B521.

This guide is divided into 5 sections. Follow all sections in the order illustrated in the guide.

Optional Step (Recommended) : Flash Stock B510

It is generally a good idea to start from a completely fresh base. Although not necessary, you will however, loose all your data and apps. Backup what is important before following. ​

Flash Stock Recovery (see Step 4 below)

Download B510 from here: https://mega.nz/#!NYgUFYLA!wEEf0f3w_6wxbzr9TYTvTquGBUhsMmRG53G8RSp2xMQ

Copy the Update.APP in the downloaded B510 ROM to dload folder in the root of your external SD card.

Power off your device.

Hold Volume Down, Volume Up and Power buttons simultaneously until you see the Honor logo. Your device will now automatically flash the whole Update.APP

Step 1 : Flashing Custom Recovery (TWRP in this case)

If you are already on TWRP, then skip this section.​

Before you follow make sure you have installed Huawei HiSuite and ADB/Fastboot Tools. If not see the links below:

Huawei HiSuite:

http://consumer.huawei.com/minisite/HiSuite_en/

ADB and Fastboot:

https://drive.google.com/open?id=0B0LG0AQ4V9FpcXRmV1BmRk1Ta1k

Extract the ADB and Fastboot zip to any preferred location.

Instructions

Download TWRP 3.0.1 Recovery. Head to this thread for download links: http://xdaforums.com/honor-4c/development/recovery-twrp-3-0-0-0-huawei-honor-4c-t3349495 Copy the downloaded recovery to the folder where you have extracted ADB and Fastboot tools.

Power off your device.

Now while holding Volume Down button attach your device to computer via USB cable. Your device will now automatically switch to Fastboot mode.

In the folder where Recovery and Fastboot tools are present, hold down left shift button and simultaneously press Right mouse button. In the dropdown menu, select Open Command Window here.

Switch to the Command Prompt window and type:

fastboot flash recovery recovery_name.img

Replace recovery_name with the downloaded recovery's file name.

You have successfully installed TWRP :victory:

Step 2 : Enable Local OTA Update option in Marshmallow

In Marshmallow, Huawei has removed the option to flash OTA updates and Update.APP through the Local Update. Lets get that option back!​

Credits to this section goes to OXALIS at 4pda.ru for making the patch to enable Local Update option in Huawei Update app.

Download the Huawei Update patch from this link: https://drive.google.com/open?id=0B0LG0AQ4V9FpUXUybmFZeTVXNDg Copy it to either your device's internal memory or a SD card.

Power off your device.

Hold Power and Volume Up buttons simultaneously to boot your device to recovery.

Install the zip downloaded in the first step though TWRP.

Step 3 : Removing Root

If your device is currently not rooted and is completely stock, you can skip this section.​

Before you follow make sure you have installed Huawei HiSuite and ADB/Fastboot Tools. If not see the links below:

Huawei HiSuite:

http://consumer.huawei.com/minisite/HiSuite_en/

ADB and Fastboot:

https://drive.google.com/open?id=0B0LG0AQ4V9FpcXRmV1BmRk1Ta1k

Extract the ADB and Fastboot zip to any preferred location.

Removing Root

Download Stock Marshmallow boot image from here: https://drive.google.com/open?id=0B0LG0AQ4V9FpY1lBVF9ubFdOSXM Copy it to the folder where you have extracted ADB and Fastboot.

Power off your device.

Now while holding Volume Down button attach your device to computer via USB cable. Your device will now automatically switch to Fastboot mode.

In the folder where Recovery and Fastboot tools are present; hold down left shift button and simultaneously press Right mouse button. In the dropdown menu, select Open Command Window here.

Switch to the Command Prompt window and type:

fastboot flash boot stock_boot_mm.img

Open SuperSU app and click on "Full Unroot" in Settings.

Your device is now unrooted.

Q. Why not just click the 'Unroot" option in SuperSU app?

Although that would work as it does the same the same thing described above i.e. replace patched ramdisk with stock backup, if the backup isn't present (such as you made a Factory Reset), your ramdisk will remain patched even though unrooted. It's good idea to revert to Stock boot.img if you ever need to root again.

Step 4 : Flashing Stock Recovery

It has been literally mentioned a thousand times that you can't flash official ROMs and OTAs through a custom recovery (such as TWRP). You have to be on Stock Recovery.​

Before you follow make sure you have installed Huawei HiSuite and ADB/Fastboot Tools. If not see the links below:

Huawei HiSuite:

http://consumer.huawei.com/minisite/HiSuite_en/

ADB and Fastboot:

https://drive.google.com/open?id=0B0LG0AQ4V9FpcXRmV1BmRk1Ta1k

Extract the ADB and Fastboot zip to any preferred location.

Instructions

Download the Marshmallow Stock EMUI Recovery from here: https://drive.google.com/open?id=0B0LG0AQ4V9FpbldwYWExOGNTUTQ Copy the recovery to the location where you have extracted ADB and Fastboot tools.

Power off your device.

Now while holding Volume Down button attach your device to computer via USB cable. Your device will now automatically switch to Fastboot mode.

In the folder where Recovery and Fastboot tools are present; hold down left shift button and simultaneously press Right mouse button. In the dropdown menu, select Open Command Window here.

Switch to the Command Prompt window and type:

fastboot flash recovery stock_recovery_mm.img

You have successfully installed Stock Recovery :victory:

Step 5 : Updating to B521

Download the B521 OTA zip from here: https://drive.google.com/file/d/0BxgU9yQssu83NTJ6eFBseS1ET3c/view?pref=2&pli=1 (Credits goes to vit755 at 4pda.ru)

Rename the downloaded zip to update.zip and copy it to dload folder in the root of your external SD card.

In your device, open Settings and tap on Update.

Tap the Menu button and then Local Update

Tap the Incremental Update option.

Your device will now reboot to install the update.

Tada! You're done! (Hit thanks if you found this guide useful)