[Huawei P9 ROMs, Kernels, Recoveries, & Other Devel] Tecalote:
Tutorial for return from NewWorld to Stock Marshmallow Firmware

If there is a reason to return from NewWorld to Marshmallow Original Stock Huawei Firmware - you can use this steps:

1) Backup what you need to backup! Use Huawei Backup and also Titanium Backup. NOTE: In the new Firmware or Rom dont restore system-apps or data from system-apps from previous system! Restore only USER-APPS. For Chat-Apps like WhatsApp, Viber, Skype use the built-in Backup function - but keep or backup the folder from those apps on internal memory (because you need them on the same place if you reinstall those apps)

Battery must have minimal 80% doing those steps....

If you have Xposed Framework installed - uninstall it (K-Settings /Xposed Settings /Install Xposed confirm - Reboot needs about 15min)

2) Open K-Settings /more settings /flash recovery - Flash official Recovery (grant Root-Permission) - this flashes Stock Recovery in half a second.

3) Download the Full Firmware (no OTA.zip) for your model, unzipp it on your PC (mostly you get update.app and meta.inf)

4) Create a folder on internal memory or external SD and name it: dload

5) Copy only update.app and meta.inf (if meta.inf is present) in this folder. After DISCONNECT USB from Phone!

6) Reboot to Stock Recovery - with Restart menu (also possible with pressing Vol+ and Power-Button at the same time as long until Recovery is displayed)

7) Wipe Cache with Stock Recovery (it uses another engine than TWRP) and do after a Factory Reset. There is no need to restart the phone to system now.

8) Press Vol- and Vol+ (in the middle) and Power-Button at the same time, until phone reboots and EMUI-Software-Installing is displayed

9) Let the EMUI-Installing finishing - it reboots automatically to system and starts the EMUI-Optimizing - wait until Language-Selection (new setup for you phone) is displayed.

Now you are back on Stock Firmware - Bootloader was automatically closed during Firmware-Installing

You can stay now on Marshmallow or update to Nougat if you like. But note: Once you are on Nougat - the Downgrade to Marshmallow is possible but not recommended (cause people reporting errors after Downgrade)

If you want to stay on Marshmallow and flash another Marshmallow based Custom Rom, continue from step 9 as follow:

9) In this case make just a short set up (You can skip the most) - but it is important to arrive the homescreen.

10) Go to Settings / About the phone and tap 7x (times) on Build-Number. It activates developer options.

11) Go to Developer options and activate USB DEBUGGING - and OEM-UNLOCK - after open Advanced settings /security and activate "Unknown Sources"

12) Connect Phone with USB to your PC (Accept the Fingerprint query with "always" on your Phone) Look, if Windows installed the right drivers so you have access to phone - if not install HiSuite http://consumer.huawei.com/minisite/HiSuite_en/index.html and make a connection with HiSuite. Allow installing HiSuite on Phone. If you have access now, close HiSuite (also in Background).

13) Copy the new Marshmallow based Rom to your Phone.

14) You need your Bootloader-Unlock-Code from Huawei!

15) With Minimal ADB and Fastboot unlock your Bootloader

16) Your phone will wiped with Factory Reset.

17) With Minimal ADB and Fastboot flash TWRP.

18) DISCONNECT USB Cable now from your Phone

19) Press Vol+ and Power-Button at the same Time until phone reboot (at the moment, Huawei Logo comes you can leave Power Button, but keep holding Vol+ until TWRP is displayed) - Reboot to TWRP takes a while

20) Set up TWRP (allow modification, set language, screen timeout, time zone...)

21) There is no need to wipe internal SD (but if you like to do this, do it at first and restart after TWRP - then you must setup TWRP again)

22) Go to Wipe, Advanced Wipe and wipe: Dalvik&Cache, Cache, data and system

23) Install the new Rom

24) Restore User-Apps, but dont restore any System-Apps (or data from it) Chat-Apps install from Playstore, and use the built-in restore function.

Huawei-Firmware-List:

Use only Marshmallow Full Firmware to retourn from NewWorld to Stock (mostly b182 or b181). Choose the right one for your model and cust! As far as I know all versions over 300 are based on Nougat (those you cannot use)

EVA-L09: http://hwmt.ru/oth/HWFF/info/view.php?find_model=eva-l09

For EVA-L09 - I would recommend following Firmware: http://www.carbontesla.com/2016/11/download-huawei-p9-b182-marshmallow-update-europe/

EVA-L19: http://hwmt.ru/oth/HWFF/info/view.php?find_model=eva-l19

EVA-L29: http://hwmt.ru/oth/HWFF/info/view.php?find_model=eva-l29

EVA-TL00: http://hwmt.ru/oth/HWFF/info/view.php?find_model=eva-tl00

EVA-ALxx: http://hwmt.ru/oth/HWFF/info/view.php?find_model=eva-AL (not sure, but maybe work on CL and DL variants)

Another Thread for Firmwares:

https://xdaforums.com/p9/development/rom-stock-rom-eva-l19c636b168-t3419586

How do debrand Huawei Phone by SRK Tool Huawei:

https://xdaforums.com/p9/how-to/vdo-guide-how-to-debrand-huawei-phone-t3410045

More debranding Stuff:

https://xdaforums.com/p9/how-to/guide-debranding-to-c432-updating-to-t3551523