[Treble-Enabled Device Development A/AB ROMS] IonDEfeso:
Sucessfully flashed onto a Mate SE (BND-L34)/Honor 7X

Less than 24 with it and so far pretty good. Havent tinkered much with it so dont take my initial impression as "absolute" and final. Here I will just explain my installation process for the benefit of people with Honor 7X/Mate SE devices that wants to try this for the first time.

As an introduction before trying this one I had the Pixel Experience 8.1 (which is very much recommend to everyone, it was great, one of if not the most stable android experience overall for me). After a few months of using it and without any noticeable bugs I did ran into a problem that was the google launcher started crashing into infinity (looping that didn't went away not even deleting the cache on the app and reinstalling it would fix it). So after that I decided it was time to try something else. So I went to try the Pixel Experience 9.0 without success which made instead try this one and here we are.

I will take a chance to make a very basic installing guide (to cover everyone knowledge levels) for people with the Honor 7X/Mate SE USA edition (BND-L24/BND-L34) . On this guide I will assume people isnt running stock (EMUI 8 or 8.1) and rather are running other customs ROMs instead and want to try this one for the first time so the first part should be avoided by those already on stock EMUI 8.

According to the instructions we have to first go back to stock EMUI 8 first, then flash the system for android 9.0 and then flash stock kernel and stock ramdisk.

Files needed:

- [AOSP 9.0] Android P System PE [The one in this thread first page, once downloaded you should rename it to system.img]

- Stock EMUI 8.0 ROM* (if going back from another custom rom you need the: update.zip, update_all_hw.zip, update_data_public.zip and the HuRUpdater_0.3.zip)

- Stock EMUI 8.0 Kernel

- Stock EMUI 8.0 Ramdisk

- TWRP for this guide (rename it to recovery.img)

Try to keep all those files ready in a folder of your choice.

I. Going back to Stock EMUI 8* (from any other custom rom already installed)

Follow this guide but instead of using his TWRP recovery use the one I provided above.
​

*Skip this step if already running stock EMUI 8 or 8.1

II. Installing Android P

1. Turn on/Restart phone after installing EMUI 8 and press volume up for 3 seconds when into the bootloader warning screen to get you into the eRecovery (or stock recovery).

2. Perform a Wipe Data/Factory Reset (your phone will restart into it).

3. Turn off phone, then connect a usb cable to your phone and press power + volume down until you log into fastboot/rescue mode.

4. In your computer look for the: system, kernel and ramdisk images youve downloaded and put in in your adb/fastboot folder then Shift + Right-Click to open a command window in that folder.

5. Then run the following commands to flash the system, kernel and ramdisk:

1. To flash OS

fastboot flash system system.img

2. To flash kernel

fastboot flash kernel kernel.img

3. To flash ramdisk

fastboot flash ramdisk ramdisk.img

4. Finally

fastboot reboot

5. Once you get to the bootloader warning screen press Volume up for three seconds and Wipe Data again then reboot.​

Welcome to Android Pie!
​

III. Installing TWRP

After you have Pie installed you can proceed to re-install TWRP again by transfering the recovery.img to the adb/fastboot folder, opening a command windows and restarting the phone into fastboot/rescue mode then running the following command:

fastboot flash recovery_ramdisk recovery.img

From there you can just root the phone with magisk or supersu, which im not going to cover in here.​

Used guides and thanks to:

rcstar6696 - For the OS and this thread, also everyone else directly or indirectly involved

zxz0O0 - HuRUpdater

steven360 - Getting back to stock EMUI super easily

XDA - How to Install TWRP

mrmazak - Stock EMUI 8.0 Files