[Honor 8 ROMs, Kernels, Recoveries, & Other Develop] Corax26:
Hi guys, I finally got around to upgrading my FRD-L09 to RR 7.1, there were some pitfalls along the way but it's finally up and running!! Special thanks to [MENTION=1240160]faeArai[/MENTION], [MENTION=7824497]Rommco05[/MENTION] and [MENTION=5933297]adriansticoid[/MENTION] who gave me very useful pointers before I took the plunge :D

Since I myself had trouble figuring out exactly what I had to do, I thought it would be useful to record exactly what I did to install the latest RR, starting from my old RR 6.0 (M), EMUI 4.x based. Most of this is based on faeArai[/MENTION]'s post, with a few tweaks and additions (some specific to my setup).

Backup all internal storage, including /sdcard! A TWRP backup will take care of the system data,but you have to backup /sdcard (internal storage) separately!

Install B131 (thanks [MENTION=1240160]faeArai[/MENTION] for the link!): extract dload/ to the microSD card, shut down, press both Vol+ and Vol-, and then the power button. I didn't need to install the stock recovery, I left TWRP there.

Once B131 is installed, the device will reboot. Apparently, installing an UPDATE.APP doesn't automatically perform a factory reset, and in my case EMUI got stuck at the boot logo. To solve this, I simply performed a factory reset by rebooting into eRecovery (press Vol+ then power for a while) and choosing the Factory reset option (and then rebooting again).

B131 will now start, set up the Wi-Fi and you should immediately be proposed the B360 update. Press Quick update, it will download the update and automatically install it (and reboot).

B360 will start. Skip all the configuration (the Wi-Fi settings should have been remembered), insert your SIM card if not already done, then go to System update in the settings where you should have the option to update to B380. Curiously, the update took longer than B360 for me.

B380 will start, go back to System update to update to B389 (same as above).

Finally, B389 starts. Go to Developer options, enable OEM unlock. We are now ready to get away from EMUI!

Power off, then plug the device to USB while pressing Vol-. Unlock the bootloader via fastboot as usual (see http://cleanimport.xda/index.php?threads/68281234/).

Enter eRecovery (Vol+ during startup), and format data. This is very important, otherwise TWRP won't be able to manipulate /data (see below).

Flash TWRP 3.1.1 (https://github.com/OpenKirin/android_device_honor_frd/releases/download/3.1.1-1/twrp-3.1.1-1-frd.img) via fastboot.

Boot TWRP (power off, press Vol+ then power), factory reset from there (at this point I don't think there's anything left to wipe, but just in case...).

Very important: check that /data is not encrypted! Despite formatting /data via eRecovery, /data was still encrypted for some reason, and RR would get stuck at the boot screen. One easy way to check that is via adb shell:

mount | grep /data

should say that /data is mounted from mmcblk0, not /dev/block/dm-0! In my case, formatting /data from eRecovery again did the trick, I'm not 100% sure what happened though... Be aware that if /data is encrypted and you try to format it via TWRP, it will fail and the partition will be unusable until formatted via eRecovery.

At last, we can flash RR N! Install RR-N-v5.8.3-20170628 first (to flash the vendor partition), then RR-N-v5.8.3-20170715, and finally your favourite OpenGApps.

Reboot and enjoy!!

As a final word, a huge thank you to the OpenKirin team, without which I would have already got rid of my Honor 8! :D (Seriously, if I liked iOS, I would have bought an iPhone, not an Android phone...)