[Huawei P9 ROMs, Kernels, Recoveries, & Other Devel] Tecalote:
This Guide show you how debrand from L09c432 to L19c432.

Note: The updated method use a new flashable zip to change oeminfo and other files from EVA-L09 to EVA-L19 (not tested yet, but it should work!)

This zip contains for L19c432b182: oeminfo, custom.bin, build.prop and lib_oeminfo_interface.so for arm and arm64

The other steps are tested, you will be at least on L19c432 - but it is not reported yet, if you have the required Dual-Sim settings in settings for using two SIM-Cards.

You do the modification at your own risk!

updated 11.03..2018:

If you are on Android 7 - downgrade to Android 6 is required (if you are already on Android 6, skip the steps for downgrade)

0) Make sure Developer Options are enabled and in there should be OEM-Unlock enabled - and if following is not enabled, enable A) ADB Debugging in charge only mode B) USB Debugging (in this order - it will not stay enabled, if you choose first USB-Debugging)

1) If your device is rooted, you must Unroot - skip this point, if you are on clean Stock Firmware.:

If you have Magisk flash Magisk Uninstaller with TWRP: http://tiny.cc/latestuninstaller

If you use SuperSU - Unroot from SuperSU.app (with restoring boot.img) - or flash Update-Unsu.zip: https://xdaforums.com/showpost.php?p=63615067 - but if you flash this zip you must restore original boot.img from your current Firmware after!

2) Original Huawei Stock Recovery from your current Firmware /or ROM must be flashed - you cannot do this steps with TWRP!

3) Download the Firmware which you currently use (update.zip), unzipp it on PC. With Huawei Extractor you can extract RECOVERY.IMG from this Firmware: https://xdaforums.com/showthread.php?t=2433454

4) Flash EMUI "RECOVERY.IMG" in Fastboot-Mode ( fastboot flash recovery RECOVERY.IMG)

5) You must downgrade to Android 6 with b300 Transition Pack for L09: http://download-c.huawei.com/download/downloadCenter?downloadId=91727&version=358124&siteCode=nl

- unzipp the update.zip on your PC and copy the UPDATE.APP to the main directory of your external SD in a folder exactly named: dload

6) Flash this UPDATE.APP with 3 Button Method (force upgrade) VOL+ and VOL- (press Key in the middle down and stay on it) and same time press Power Button /Phone reboots. Soon as Huawei Logo comes you can release only Power Button but keep pressing down Vol+ and Vol- until EMUI-Software-Installing begin.... After 100% Phone reboot and you can look into settings /about phone - you should be then on L09c900b300

7) Now delete UPDATE.APP in dload folder and download b182 for L09: http://update.hicloud.com:8180/TDS/data/files/p3/s15/G1079/g104/v63880/f1/full/update.zip

- unzipp the FW update.zip on your PC and copy the UPDATE.APP and META-INF to the dload folder on external SD

8) Flash this b182 for L09 with same method described in step 6 - after you can see in settings/about phone you are on L09c900b182 - clean up after dload folder

- in settings/about phone enable Developer Options (7x click on build number) and in Developer Options enable USB Debugging (OEM-Unlock should be always enabled)

Now check in Fastboot Mode if your Bootloader is still open (FRP unlocked, Bootloader unlocked) , if not, you must reopen it (always same Unock Code)

9) Download b182 for L19: http://update.hicloud.com:8180/TDS/data/files/p3/s15/G1079/g104/v74994/f1/full/update.zip

- unzipp update.zip on your PC and copy the new UPDATE.APP and META-INF to the dload folder - but dont flash it right now!

10) Download TWRP for Android 6 (not the one for Android 7!!): https://www.androidfilehost.com/?fid=457095661767122229

- flash TWRP for Android 6 and boot to TWRP directly after flashing, allow system modification.

11) Download L19c432b182-oeminfo-custom.bin_flash.zip: https://www.androidfilehost.com/?fid=890129502657589952

This zip contains for L19c432b182: oeminfo, custom.bin, build.prop and lib_oeminfo_interface.so for arm and arm64

Check MD5: 9e6de17690e06eb4b5da247dbdbb06e8

12) Copy this flash zip to the external SD of your P9 and disconnect USB from your Device!

13) Boot to TWRP and make Nandroid Backup of the current state of your Phone - Backup: cust, data, oeminfo, system - you can restore in the worst case

14) Change now oeminfo/custom bin by flashing the downloaded zip: L19c432b182-oeminfo-custom.bin_flash.zip with TWRP - after use: Reboot - but ATTENTION:

15) In that moment the phone is restarting press Vol+ and Vol- (in the middle) down and hold this position until phone is rebooted to EMUI Software Installing (b182 for EVA-L19 from dload folder will be installing now).

If you see on screen text with red colour - ignore it, just press Vol+ and Vol- down, if it does not help, press also Power Button to reboot, but keep pressing Vol+ and Vol- because b182 must flashed at this point!

16) Now b182 for L19 will be flashed ( from dload folder!) Wait until 100% is ready and device will restart, but in the moment press down only Vol+ to boot P9 into Stock Recovery instead of system. In Stock Recovery perform Wipe Cache Partition and do Factoryreset - the Factoryreset must be 100% successful!

If on Point 16 Software Installing failed, boot with Vol+ and Power Button to Stock Recovery, make Wipe Cache and Factoryreset - then Restart and press now Vol+ and Vol- again to repeat step 16 - or if you was not quick enaugh at Point 16 with the Buttons and you was booted to system instead to EMUI Software Installing - you see a field to enter a password (in this case use your Google Password) Phone will do Factoryreset with low-lewel-wipe after (but not always 100% succesful) if not succesful - in any case (if succesful or not) - flashing again b182 for L19 from settings (next step 17) is required!

17) Do second Factoryreset but now from settings /advanced settings / backup reset / Factory data reset / - and be sure you have enabled: "Erase internal storage" - this will do a low-lewel-wipe, which is required (it must be 100% succesful)

18) You are now sure on L19c432b182 - but check settings, if you have Dual-Sim settings (this is not tested/reported yet). Clean up dload folder.

You will receive then OTA to b383 - important: SIM Cards must be now inserted - if not: no OTA

19) Do all available OTAs and on last OTA make another Factoryreset with wipe of internal storage directly from settings/advanced settings/backup restore/factoryreset

20) After last OTA you can use my method in #2 of this Thread to update to higher Firmware.