Develop Bugs

Boot Loop stuck in Animation help.

Hey everyone. I know there are already a few threads with boot loop animations, and am having difficulties finding the same situation as what I'm going through. Here is what the phone used to have before it randomly started looping:
Rooted - with Stock rom, using ClockwordMod Recovery 5.5.0.2
Used Go Launcher Theme ( if that even matters )
No additional roms installed or anything, the phone is 3 months old.
Ok here is where I'm stuck. I understand I should reflash somethings like recovery image or something, but I'm stuck with one big problem. My computer and phone don't recognize using the USB mount.
The message I get is called "Unable to open lunfile ( no such file or directory)
Here's what screens I can get to:
1. Hold vol up/down while holding power ( the little android with its belly open, and the options Start - Restart Bootloader - Recovery mode - Power Off )
2. Hold vol down - ODIN mode, with the START option only
I can access WMD recovery and factory reset, Try to install my old backup, nothing works at all in that area, no matter what I do.
Can someone advise me a step by step way of getting my computer to recognize my phone, so that I am able to do fastboot, or reflash, or anything to get my phone working again. I can't access my internal memory at all.
It's even possible that I've read too much, and my frustration is getting in the way, if so I apologize! Some guidance would be greatly appreciated!
Thanks in advance of course! I need my phone for business!
Cheers,

Install the drivers on a computer then use fastboot oem unlock. Or just factory reset it from within recovery.
Sent from my Galaxy Nexus using Tapatalk 2 Beta-4

Try my siggy.
I'm not sure about the exact error:
But the link there will get you the correct drivers.
Also, as stated...try to factory reset.
You'll lose your apps/data that way though =/
Hopefully you can get the driver installed and get your computer to recognize.
If so, follow this to back up your apps:
http://forum.xda-developers.com/showthread.php?t=1420351

Have exactly the same setup as you (rooted/stock/CWM) and had the animation bootloop - animation would just loop until a battery pull.
Only thing that solved it was a factory reset from recovery. Been working fine for the 4 weeks since. No need for any reflashing etc. Titanium recoveries have all worked fine as well. Didn't try my Nandroid backup as I thought that may still have the 'fault' built in.

I had a boot loop for every from I tried to flash...wat fixed it was before flashing u need to wipe system data and wipe the cache in the recovery...ie a clean install...then every rom I tried worked...so I think ur missing that crucial step coz it worked for me
Sent from my Galaxy Nexus using Tapatalk

Hey guys, as stated above I've done numerous factory resets, it still seems to boot. I will for sure try to get the drivers installed so my phone is recongised by the computer, but would need step-by-step assistance when doing fastboot, or whatever the next step is.
Looking for more help though! Keep em coming!

?
Any other ideas?
Thanks!

Ok guys, so here's where I'm at now. I've used Jubakuba's sticky link, located here:
http://forum.xda-developers.com/showthread.php?t=1529058
Everything is able to be recognized up to the point where it says "Put the su.zip on your phone."
Since I cannot access my phone contents, since I keep getting this "Unable to open lunfile ( no such file or directory), it does not allow me to add anything to my phone.
I re-installed CWD as stated in the list of things to do, and all that went well. But I have the same issue, I tried factory resetting all that. erase cache, and still stuck with the same issue.
What's my next step now peeps? Looking for a quick answer as I have time to do it tonight!

Edit***
Just tried this trick: but it says it does not recognize the device?? what is going on! Please help someone! Thanks!
Panic Section! (Something is Wrong)
Q: My phone won't boot!
A: The easiest option is to get into recovery and restore a nandroid using the above guide (pull battery to put phone in an off-state if needed).
However, more advanced options are available if you don't have a nandroid available (You're naughty).
Do you have another rom .zip available on your SD card? If so, simply use the above guide for installing a rom to get you booting again.
If not, you can download one on your PC. Boot into fastboot (the green Android with open chest menu).
Move the .zip to the C:\android-sdk-windows\platform-tools folder.
Open ADB.
Change the NAMEOFZIP.zip below to the correct file name...and perform the action.

Surely your computer recognizes your phone. Otherwise how were you able to unlock the bootloader and flash the recovery?
And I've never seen that error message before. It doesn't even make any sense to me. Where are you seeing it? On your phone or on your computer? And in what context? What are you trying to do when it shows up?
If your phone isn't booting I'm not sure that you can copy any files to it yet. (Maybe you can use adb in clockworkmod? I'm not sure) What I do know you can do is flash the stock ROM and start over.
Download the image from Google here:
http://code.google.com/android/nexus/images.html
Here's a instructions for the GSM version:
http://forum.xda-developers.com/showthread.php?t=1366806
For the Verizon version, I can't find the thread at the moment but you just replace the filenames and also there's 2 radios to flash so:
fastboot flash radio *filename*
fastboot reboot-bootloader
fastboot flash radio-cmda *filename*

"Unable to open lunfile ( no such file or directory) appears on the phone, in CWD mode, when trying to attempt "mount Usb" to be able to access my internal storage .
I am attempting your thoughts right now.
I will post with results

Ok I tried to do this step. This is the outcome I received on the computer after even typing the first step:
'fastboot-windows' is not recognized as aninternal or external command, operable program or batch file.
A thing to stress, I'm not sure how to do step 1: 1) Take a Nandroid Backup if you have CWM installed.
EDIT***
GREAT NEWS!
used this setup!
http://android.modaco.com/topic/348161-01-feb-r4-superboot-rooting-the-gsm-lte-galaxy-nexus/
and it worked!
Thank you everyone! Going to play with my phone and make sure it all works!

Macinshak said:
Ok here is where I'm stuck. I understand I should reflash somethings like recovery image or something, but I'm stuck with one big problem. My computer and phone don't recognize using the USB mount.
The message I get is called "Unable to open lunfile ( no such file or directory)
Click to expand...
Click to collapse
the problem is when that happen?? when ur phone is booted and u plug the usb cable to ur pc? or when u are under recovery and want mount the usb mass storage? the second one doesn't work

is it possible that my internal storage to be wiped out completely using xFSTK

My Zenfone 2 got bricked without me doing anything to it. It happened when I tried to charge my phone as I normally would. The next thing I knew, I saw a hanging USB logo. All possible solution offered around the web failed to save it. Then I tried the guide offered in this forum. manage to get into fastboot but failed to flash the firmware using all the possible solution suggested. When I tried to install file using CWM and TWRP I also get the
E:/ unable to find partition.
E:/ unable to mount cache.
E:/ unable to data
etc...
when I tried to ADB sideload my device was immediately disconnected from my pc. One thing that I found out from TWRP is that my internal storage 0 mb.
So my question, is it possible that my internal storage to be wiped out completely when I first tried to unbrick my phone using xFSTK to get into fastboot?
If so, how can I recover from this problem? Since my device is already hard brick, I'm willing to tried any possible solution to get it back to life. but I'm gonna give it a try. Another concern I have at this moment, I used to get the USB hanging screen but now no longer.

How about yours phone? In facts, xfstk works on first partition only, which contains dnx, ifwi and fastboot, so it doesn't harm your phone anyway. I'm sure about that . If u can access fastboot, it's easier than you think. Just download "raw" firmware (.raw extension), then use Asus Flash Tool to flash that ".raw" firmware to your phone first. After that you can flash any other Rom u want like normal. Or open that ".raw" firmware with any archive manager like winrar, 7zip...,extract it to somewhere, go to extracted folder, u will see 2 .bat file, now either refer 2 files to flash by manually, or execute it in cmd directly.
Sent from my ASUS_Z00A using Tapatalk

5x Hard Bricked??

I think I've done goofed my nexus.
Yesterday, I made a backup of my phone, and then booted it up. Everything was working fine prior to the backup, but as soon as I booted it after making the backup, it got stuck on the google logo. I tried restarting it several times, but it's just been stuck in a bootloop ever since. I've tried numerous things, like formatting it, flashing factory images, and so on, but it turns out fastboot won't detect my device. ADB detects my device fine, but only in recovery. As far as I know, I don't have usb debugging enabled (since I formatted it). It currently has no OS since I formatted it. I've tried installing stock android since formatting it but it still gets stuck in a bootloop.
All my drivers are correct (I've re-installed them probably 10 times by now), and the images aren't corrupted (as far as I know).
I've run out of ideas, as I've been trying to figure this out for the past 2 days with no success. Any help would be appreciated.

I've had a similar issue a couple times after doing something stupid (ADB or FASTBOOT could not detect the phone). The fix was to look in Windows Device Manager and make sure the phone really was detected and a driver installed. Windows would say that it could not find a driver but telling it to install manually did the trick..... as I recall there were a couple driver choices, so it might be trieal and error. Might not be the issue in your case since it does sound like the hardware has a problem, but worth looking into?
Paul

pgoelz said:
I've had a similar issue a couple times after doing something stupid (ADB or FASTBOOT could not detect the phone). The fix was to look in Windows Device Manager and make sure the phone really was detected and a driver installed. Windows would say that it could not find a driver but telling it to install manually did the trick..... as I recall there were a couple driver choices, so it might be trieal and error. Might not be the issue in your case since it does sound like the hardware has a problem, but worth looking into?
Paul
Click to expand...
Click to collapse
I've re-installed the drivers a couple of times now, and it doesn't seem to be fixing the problem.
I don't think it's a hardware problem, because I don't see what making a backup would do to the hardware of the phone (of course, I don't really know much about the hardware, so I might be wrong.) Thanks for the help, though!

ItsMason said:
I've re-installed the drivers a couple of times now, and it doesn't seem to be fixing the problem.
I don't think it's a hardware problem, because I don't see what making a backup would do to the hardware of the phone (of course, I don't really know much about the hardware, so I might be wrong.) Thanks for the help, though!
Click to expand...
Click to collapse
Hi, since you're communicating with the device via ADB and can boot to recovery, I'm pretty sure you can still do something about it. I've had this issue and I can recommend starting to read up on Ubuntu or some type of Linux with a decent user interface. It's easier for starters.
You see, if you don't detect the device via the 'fastboot devices' command, then you have one of two big problems:
a) drivers are messed up - it implies you uninstall everything from Device Manager related to ADB / Bootloader interface. After that, shut off the phone, connect your type-c usb cable, boot up the phone into bootloader and let it install the drivers again (I didn't have much success with this but I read others have. Worth a try)
b) something messed up deeper, as in device permissions. When I had the issue, I used Mint (a Debian distribution) and installed all the drivers via the command line there. After that, when I ran fastboot devices, I got something. It was my lost N5x showing with 'no permissions' and no serial ID. I ran 'sudo fastboot devices' and lo' and behold, I saw the device. After that, I just used sudo fastboot flash recovery/system/etc with it and that was it.

exige34 said:
Hi, since you're communicating with the device via ADB and can boot to recovery, I'm pretty sure you can still do something about it. I've had this issue and I can recommend starting to read up on Ubuntu or some type of Linux with a decent user interface. It's easier for starters.
You see, if you don't detect the device via the 'fastboot devices' command, then you have one of two big problems:
a) drivers are messed up - it implies you uninstall everything from Device Manager related to ADB / Bootloader interface. After that, shut off the phone, connect your type-c usb cable, boot up the phone into bootloader and let it install the drivers again (I didn't have much success with this but I read others have. Worth a try)
b) something messed up deeper, as in device permissions. When I had the issue, I used Mint (a Debian distribution) and installed all the drivers via the command line there. After that, when I ran fastboot devices, I got something. It was my lost N5x showing with 'no permissions' and no serial ID. I ran 'sudo fastboot devices' and lo' and behold, I saw the device. After that, I just used sudo fastboot flash recovery/system/etc with it and that was it.
Click to expand...
Click to collapse
I made some progress: my device is now detected in fastboot. I have literally absolutely no clue what happened. I guess it was a bit of randomness or luck or something (maybe wacky and goofy). I've done some flashing - I've flashed system, boot, recovery, cache, data, and radio, but it's still stuck in a bootloop. I don't know what's going on it with it now, but it seems like I haven't made any progress with fastboot.

ItsMason said:
I think I've done goofed my nexus.
Yesterday, I made a backup of my phone, and then booted it up. Everything was working fine prior to the backup, but as soon as I booted it after making the backup, it got stuck on the google logo. I tried restarting it several times, but it's just been stuck in a bootloop ever since. I've tried numerous things, like formatting it, flashing factory images, and so on, but it turns out fastboot won't detect my device. ADB detects my device fine, but only in recovery. As far as I know, I don't have usb debugging enabled (since I formatted it). It currently has no OS since I formatted it. I've tried installing stock android since formatting it but it still gets stuck in a bootloop.
All my drivers are correct (I've re-installed them probably 10 times by now), and the images aren't corrupted (as far as I know).
I've run out of ideas, as I've been trying to figure this out for the past 2 days with no success. Any help would be appreciated.
Click to expand...
Click to collapse
Do you use 3.02.1. Twrp

Since you mention ADB works fine from recovery, have you tried to adb push a rom zip, and then flash it from your recovery?
Code:
adb push "/path/to/rom.zip" /data/media

ItsMason said:
I made some progress: my device is now detected in fastboot. I have literally absolutely no clue what happened. I guess it was a bit of randomness or luck or something (maybe wacky and goofy). I've done some flashing - I've flashed system, boot, recovery, cache, data, and radio, but it's still stuck in a bootloop. I don't know what's going on it with it now, but it seems like I haven't made any progress with fastboot.
Click to expand...
Click to collapse
Good. I see you mention flashing system, boot, recovery, cache(?), data(?) and radio. What do you mean by flash cache&data? You mean you've cleaned it? Formatting data is not usually a thing you have to do to recover from a bootloop.
What ROM have you flashed? Are you flashing stock? It's important you give more details so I can help you.
Have you flashed vendor.img? If you have been on a ROM that had it's own vendor.img and you went back to stock, then the vendor.imgs are different enough to cause a bootloop.
If all and all fails, we just want to see your system running so I'd recommend drop everything you are doing and follow these steps:
1. Access recovery (make sure you're using v 3.0.2.2)
2. Tap Wipe - > Advanced Wipe - > And check:
Dalvik / ART Cache
System
Internal Storage
Cache
3. Go to -> Pixel ROM (7.1.1) Get V 3.0 which was just uploaded recently. Please note it comes preconfigured with Gapps so no need to get that
4. You have to unzip the archive and you will see all the necessary img files (includes boot/vendor which are critical for boot). I strongly recommend manually flashing them. You can open the flash-all.bat file with a .txt editor and just follow the steps there.
After you have finished these steps, you should be free of a bootloop. From there, it is your decision where you. Either stay on a stock ROM or flash safely and always remember that you can make a backup and flash that backup in case you bootloop.
Good luck.
EDIT
Decay3 said:
Since you mention ADB works fine from recovery, have you tried to adb push a rom zip, and then flash it from your recovery?
Click to expand...
Click to collapse
I think his problem is deeper than a /system error. I'm guessing the wrong boot/vendor is flashed for the ROM he is trying to install and trying to guess which ROM would work on his current config would take more time than just starting from a clean flash.

Thanks for the help guys, but I gave up. I contacted Google and they sent me a replacement. Sorry for kind of wasting time.

I think I bricked my ZE551ML_Z00A

Hi everyone, I think I bricked my ZE551ML by being very very dumb, how did I come in such troubles? Well I'll explain you the whole story.
Usually I'm quite good with IT but I'm new to Android and I wanted to install Lineageos because I don't like Asus's ROM, so I searched tutorials and I found the lineage website tutorial at first it didn't seem like a hard task for me, so I started following the tutorial and I got stopped first with trying to get twrp-3.1.1-0-Z00A on the device but didn't seem to work so I tried an older version witch didn't worked too, so I came to xda to get the twrp_z00a_v24_repack and it worked (so well that I erased the system without saving anything just in case but I saved myself by getting the Asus ROM and pushing it to /sdcard/ ) so I attempted to install Lineage (that time with a save) but it gave me the "error executing updater binary in zip" so I searched on the Internet and it seemed that I had to root the phone so I downloaded addonsu-14.1-x86-signed from the Lineageos website and ran it on twrp and it told me that it worked so I wiped the system (I still got the backup) and tried to install Lineage but the same error showed up so I was thinking "Hmm maybe due to TWRP being an old version it might not work if it's not updated" so I rebooted to fastboot and then did fastboot flash recovery twrp-3.1.1-0-Z00A and tried to go in recovery, the phone rebooted, the splashscreen showed and it got to a screen similar to the splashscreen and did nothing (just heard the plug-in device sound in Windows), when I try to shut down and push the power + "+" Button it just starts as normal and the fastboot mode doesn't show.
So that's where I am, if someone could do a dumbproof step by step tutorial on how to unbrick that thing and then install Lineageos that would be so great.
Thank so much to the person (or people) that will help me
PS: I tried to search how to get out of this mess but I didn't understood all of it so I didn't wanted to get in more troubles.

Yuno17 said:
Hi everyone, I think I bricked my ZE551ML by being very very dumb, how did I come in such troubles? Well I'll explain you the whole story.
Usually I'm quite good with IT but I'm new to Android and I wanted to install Lineageos because I don't like Asus's ROM, so I searched tutorials and I found the lineage website tutorial at first it didn't seem like a hard task for me, so I started following the tutorial and I got stopped first with trying to get twrp-3.1.1-0-Z00A on the device but didn't seem to work so I tried an older version witch didn't worked too, so I came to xda to get the twrp_z00a_v24_repack and it worked (so well that I erased the system without saving anything just in case but I saved myself by getting the Asus ROM and pushing it to /sdcard/ ) so I attempted to install Lineage (that time with a save) but it gave me the "error executing updater binary in zip" so I searched on the Internet and it seemed that I had to root the phone so I downloaded addonsu-14.1-x86-signed from the Lineageos website and ran it on twrp and it told me that it worked so I wiped the system (I still got the backup) and tried to install Lineage but the same error showed up so I was thinking "Hmm maybe due to TWRP being an old version it might not work if it's not updated" so I rebooted to fastboot and then did fastboot flash recovery twrp-3.1.1-0-Z00A and tried to go in recovery, the phone rebooted, the splashscreen showed and it got to a screen similar to the splashscreen and did nothing (just heard the plug-in device sound in Windows), when I try to shut down and push the power + "+" Button it just starts as normal and the fastboot mode doesn't show.
So that's where I am, if someone could do a dumbproof step by step tutorial on how to unbrick that thing and then install Lineageos that would be so great.
Thank so much to the person (or people) that will help me
PS: I tried to search how to get out of this mess but I didn't understood all of it so I didn't wanted to get in more troubles.
Click to expand...
Click to collapse
if you are able to access recovery then dd fastboot there. if no recovery, no fastboot, no system there isonly option left. go to below thread and do step by step as suggested.. after you get fastboot mode back, do not use asus flash tool use commands to flash raw firmware see section flash firmware without AFT
https://forum.xda-developers.com/zenfone2/help/thead-bricked-phone-updating-to-mm-tips-t3452785

sukhwant717 said:
if you are able to access recovery then dd fastboot there. if no recovery, no fastboot, no system there isonly option left. go to below thread and do step by step as suggested.. after you get fastboot mode back, do not use asus flash tool use commands to flash raw firmware see section flash firmware without AFT
https://forum.xda-developers.com/zenfone2/help/thead-bricked-phone-updating-to-mm-tips-t3452785
Click to expand...
Click to collapse
Hi, thanks for the reply, I don't know if I have to post it here or on the guide but xFSTK-downloader just won't run (Windows 10 1151) and it doesn't show up in task manager (even when the antivirus is disabled).
Have you got an idea on why it doesn't work?

Yuno17 said:
Hi, thanks for the reply, I don't know if I have to post it here or on the guide but xFSTK-downloader just won't run (Windows 10 1151) and it doesn't show up in task manager (even when the antivirus is disabled).
Have you got an idea on why it doesn't work?
Click to expand...
Click to collapse
very first of all uninstall everything especially i soc drivers and xFSTK. then disable driver signature enforcement. and go to thread above posted and do step by step.
how to disable signature enforcement and install driver on win 10 see in thread above

My Honor 7x BND-L21 is quite broken, need help

Hello, sorry for the generic title, but i'm quite the noob about android modding and stuff.
Anyway I wanted to root my phone, just to stream some music to my stereo system. How naive I was...
So I unlocked the bootloader, installed twrp with adb and SuperSU with twrp. Everything was fine and phone was rooted but my past naive me thought "well let's try a custom rom, why not". So I went forth and downloaded some stuff from getdroidtips and what I understood is that all I needed to do was to do a wipe, then install the zip file via twrp. I did that and didn't work. After that I realized I made a crucial mistake: I didn't backup my phone from twrp, so I was there with no OS, quite panicked and frustrated. So I tried some other roms, finally I got one that worked, this: https://forum.xda-developers.com/honor-7x/development/openkirin-aosp-8-0-honor-7x-t3746257
It works but it's barebones and on boot it shows a message: "There's an internal problem with your device. Contact your manifacturer for details.". So, I tried recovering from HiSuite, recovery mode etc but nothing worked, I reinstalled SuperSU in the new OS via twrp to see if that would help somehow, but no. in the end I had the even more naive thought that maybe unrooting would allow me to repair via hi suite or something, so I mindlessly selected "complete unroot" on the SuperSU app, and this was the second big mistake, the process somehow ****ed up the twrp install and it no longer works. Instead, if I try to enter twrp with power button + volume up button, it shows the regular "your phone has been unlocked" screen and then comes up for a split second a black screen with, on the bottom half of the screen the "no command" logo, under it some lines of code that I can't read. It suddenly disappears and sometimes enters in a bootloop showing this screen and powering off every time.
If I keep power button pressed bootloop ends and the phone boots "regularly" in the openkirin OS.
I tried reinstalling twrp the same way I did the first time. No error on adb but same no command behaviour
So what I got now is:
kind of bootlooping no command window
openkirin OS with internal problem message
fastboot and rescue mode
it seems to work on adb (everything is fine if I type adb devices)
not working HiSuite recovery
not working Huawei eRecovery
not working download mode (I guess? the power+volume up+volume down combination)
Maybe I should mention I also did a data wipe (?? the option on the right next to "advanced wipe" in the Wipe screen, if I remember correctly) in twrp before installing openkirin, it was suggested on a yt video about how to install openkirin. And that, at a stage I tried using MultiTool but it gives me an error: "exception during a web client request. Error#9", while at the bottom left it says "downloading AdbWinUsbApi.dll..."
Sorry for the general noobishness and the bad english that might be there.
So, any tips for bringing back the phone to normal? Or at least repair twrp??
Please help, I hate needing to throw this phone away just because I wanted to stream some music and because of a couple of stupid errors

Sorry for not answering earlier. It seems, between TWRP and stock recovery, you have messed up I think. When there is no proper recovery it become difficult to bring back the phone. You should try to put it in fastboot mode first, by powering off, pressing the volume lower button and connecting it to computer. Try installing TWRP and flash a custom rom other than openkirin from there if possible. Fastboot is the choice to go if recovery is messed up.

sdivk said:
Sorry for not answering earlier. It seems, between TWRP and stock recovery, you have messed up I think. When there is no proper recovery it become difficult to bring back the phone. You should try to put it in fastboot mode first, by powering off, pressing the volume lower button and connecting it to computer. Try installing TWRP and flash a custom rom other than openkirin from there if possible. Fastboot is the choice to go if recovery is messed up.
Click to expand...
Click to collapse
No worries, I managed to fix it anyway. Some things might be obvious but I'll share what I did nevertheless, in case some other newbie finds himself in a similar situation.
So there was seemingly no way of reinstalling twrp nor the stock recovery. But luck came my way and by almost random clicking I found out that, even if multitool closed as soon as I clicked the ok button in the error message, if I simply ignored the error, the program worked just fine (as I write this I installed another version and it gave no error message). So I played with it a bit and found out that it can flash twrp and it does not need a file from you, it already has a twrp version ready to install. I did that and it worked. It looks like the first twrp file I used didn't work anymore or was someway corrupted by the countless things I tried. So, with twrp working again I was able to backup the sloppy openkiring OS and try the unbrick tool. So I browsed the internet for a guide. Guides always mention as the first step for unbricking using the VENDOR.img file located inside a full stock rom. Problem is, 99% of the times they provide a rom without the needed file. So after some tries I found a good complete stock rom with the VENDOR.img here: drive.google.com/file/d/1tjHefytEWbpuV1f4YjX8AaSMzT6jr8TQ/view but I can't remember which forum/site I found it in.
I followed the guide which involves:
-extracting the UPDATE.APP file contained in the provided zip with huawei extractor tool into an X folder on your pc
-copying the VENDOR.img file contained in the X folder, on the root folder of the sd card
-backing up OS (if there's any) via twrp (I had something like 50 partitions, I guess that was messing things up a bit, but for safety I backed them all up)
-doing an advanced wipe from twrp selecting ALL checkboxes BESIDES the SDcard of course
-flashing the vendor.img file via twrp selecting the "Vendor" partition when prompted
-downloading the update_full_[your model]_hw_[your region].zip file, in my case update_full_BND-L21C_hw_eu.zip
-extracting the UPDATE.APP file contained in update_full_BND-L21C_hw_eu.zip with Huawei extractor tool in some other folder Y
-looking for a file named cust.img/CUST.img/version.img/other_name.img (I don't know which other names it can have, I was lucky and had a VERSION.img file in it)
-rename the cust.img/CUST.img/version.img/other_name.img to CUST.img and copy it from the Y folder to the X folder
-boot your phone into fastboot mode
-connect phone to multitool via usb and select the "unbrick" tab
-there, Multitool asks for a folder, give it the X folder. There are some checkmarks on the Multitool "unbrick" page. 4/5 of them should become checked after the folder input. In my case the first 4
-then, simply press the unbrick button
-wait and pray (it can look like it freezes while it's copying the system.img file but wait, it'll be fine)
So I did that and it worked flawlessly, the phone booted slowly but surely into EMUI 5.1 with Android 7.0 I think and everything was fine.
At that point I had a working OS and a working twrp but wanted to go back to the OS I was used to, Android 8.something so, I tried connecting the thing to HiSuite and it automatically asked if I wanted to update, not to 8.something but to 9.1. I thought "SURE I DO!" and updated flawlessly (I thought 9.1 hadn't even been released here in Italy).
When it booted I found out the new OS was working like an antivirusless xp pc: it didn't recognise the SIM, it would crash every 20 seconds, app downloads got stuck at 99%, if it felt like it, it rebooted, pc connection was not stable. Besides, the update being "official" and installed from "trusted" sources (HiSuite), it completely wiped twrp.
And that was the "OH ****, here we go again" moment: no twrp and worse-than-ever-working OS.
So because of the new EMUI version, I guess, Multitool kept recognizing the phone but stopped offering its own recovery, eRecovery, twrp files available for flashing. I was completely frustrated with all of this and decided to give up, but I made the last effort: I tried the relock function in multitool. So I provided the key, pressed relock, waited, prayed, and finally cheered. It worked like a charm. Phone runs now on EMUI 9.1 with locked bootloader without problems. Finally
So I guess in the end I payed 4 euros for a nice update, a painful and frustrating trip into android modding and a lesson : never do android modding!
no, just kidding, don't do it just if you are a newbie AND you don't want to risk to throw the phone in the grabage.
In all other cases consider it carefully
Oh, and also, God bless the MT Team and Russia altogether!! thanks

Quite an experience. All the best. ?

Lol sounds fun. I've bricked my Huawei Mate SE/Honor 7x more times than I can count. I'm just awaiting my 9.1. I want my GPU Turbo! Is it as good as it's supposed to be?