[Huawei Mate 10  Questions & Answers] ItzYeho:
So, about like a week ago, I made a post on XDA developers named "Well, I f**ked up. Badly.." and basically, this is what it contained.

Alright, here goes.

So one day I was interested in flashing a new custom ROM (Preferably LineageOS) to my Huawei Mate 10 Lite. Long story short, it's now soft bricked. Only TWRP is working.

But, that's not enough information. Here's the fully story.

After realizing I could not get the Bootloader unlock code using the official method, I've tried DCUnlocker. I paid, and got my code.

I've installed HiSuite, 274829 drivers and finally unlocked the Bootloader. Now, the phone said "This device is unlocked and can't be trusted", but it booted fine. YES!

After that, I downloaded LineageOS 15.1 and flashed it. Before flashing it, I formatted everything, wiped cashe, davlick ect... And.. made my biggest mistake.

Not making a nandroid backup (dammit).

Don't ask me why, I thought it would go well (ugh).

Anyways, I flashed it, error 7. Alright, removed the assert lines. Flashed it again, and it worked, but right at the end, another error? It was error 7, again, but a little different.

This time, it said "failed to mount /dev/block/bootdevice/by-name/vendor at /vendor: device or resource busy"

Okay, now I'm starting to get worried. Like, REALLY WORRIED.

It also said it failed to execute a line in the updater script, one of the last lines. But I would not delete it, just in case.

When I tried to boot, nothing. Went back to Google.

At this point, I learned that any Treble ROM will NOT work with Android version of 7.1. shhhiiii

I was on EMUI 5.1 aka 7.0, and this was worrying. At this point, I tried to return to EMUI 5.1, but since there was no backup, well...... To Google we go!

I did not find any stock room that running EMUI 5.1, but only found EMUI 8.0. I did find a stock room on 7.1, but I'm not paying 15 dollars for it. Not about that life.

I tried the dload method, but apparently my sdcard is on FAT32, and because of that I cannot upload the UPDATE.APP to it.

I've also tried eRecovery, but to no avail. "Failed to get package".

So now I'm stuck on a couple of options, and I need help from you, the XDA community.

1) Remove the line that's causing the issue but at the cost of it maybe not working

2) Somehow format the sdcard and somehow upload the update.app to it

3) Somehow update Android's system to Project Treble, although not sure it's possible since there is no OS.

4) ?????????????????

Please, help me. I'm in hell right now.

Anyways, I've tried restoring the phone for 3 days straight to EMUI stock rom, so I could update it manually to Oreo 8.0 and THEN install LineageOS 15.1. However, I literally could not find ANY SINGLE ROM on planet earth for Huawei Mate 10 Lite, on EMUI 5.1. I was so desperate to fix the phone that I just gave up and installed Elemental which was based on EMUI 5.1. Sure, phone working great, but not what I wanted.

I wanted LineageOS 15.1, not a rom based on EMUI. So, my question is, how do I update it to 8.0?

In the post, people suggested to manually flash the stock rom (8.0), but I couldn't find the stock rom. Also, yes, I tried TeamMT's site, xml tree not working blah blah blah site's dead.

So, what do I do?