Help!! Hard Bricked Mi3w After Flashing 6.3.17

[Mister Bean]

I seem to have hardbricked my Mi3W 16Gb after attempting to flash multi_cancro_6.3.17_v7-6.0:
after flashing from TWRP and rebooting, now i have a black screen, no lights, nothing!! Access to Recovery or Fastboot is impossible, nothing happens on the screen: when I hold reboot alone, reboot with vol up or down, nothing happens on the screen...

Connected to a Windows PC, it detects a QSHSB_BULK:

and tries to mount 7 unrecognised partitions but asks to format them..

I have to admit: I have previously trying to install xaiomi.eu Marshmallow rom without success. I kept getting failed flashes with a failed to mount /data error message and the script fails.
I then went to trying XenonHD and Ressurrection Remix custom roms, and had to modify the system1 partition to 1,2Gb (found at thread-129903-1-1.html on en.miui.com to make the RR work...
I am thus on TWRP3.0 and wanted to come back to miui rom, so I wiped dalvik cache and data, the flashed xiaomi.eu_multi_cancro_6.3.17_v7-6.0.zip then UPDATE-SuperSU-v2.65-20151226141550.zip for root as per the instructions here:

On flashing the rom I got the same failed to mount /data: resource or devece busy message but this time the script finished with succes, same for the SuperSU zip. Then I rebooted and since then black screen!!!
I have TitaniumBackup and TWRP Nandriod backups of working custom roms...but obviously they are useless if I can't access Fastboot or Recovery!!

Anyone have any suggestions?

 

[Pertti Kosunen]

http://forum.xda-developers.com/xiaomi-mi-3/general/howto-how-to-unbreak-xiaomi-mi-3-to-t3027869

Put chinese dev rom factory image to merge partitions. Download xiaomi.eu 6.3.24 to internal memory. Install cancro TWRP in fastboot mode, boot directly to recovery, wipe data/cache/dalvik, install xiaomi.eu rom.

 

[Mister Bean]

Thanks for your quick reply!! But....fastboot & recovery are inaccessible :'(

EDIT: Idiot that I am I didn't see the link in your post!! Definitely looks like the article I've been looking for, Thank you sooooo much!
Millions of apologies I obviously have not researched fully, I'm off to read the post!

 

[Vinayak s]

Same has happened with me twice. What I do to recover is, connect my phone with pc and use the mi flash application to fastboot flash my most reliable fastboot rom. The phone screen may be blank but the mi flash always recognises a device is connected. And the fastboot flashing procedure remains same

 

[Mister Bean]

http://forum.xda-developers.com/xiaomi-mi-3/general/howto-how-to-unbreak-xiaomi-mi-3-to-t3027869

Put Chinese dev rom factory image to merge partitions. Download xiaomi.eu 6.3.24 to internal memory. Install cancro TWRP in fastboot mode, boot directly to recovery, wipe data/cache/dalvik, install xiaomi.eu rom.

Woohoo!! Finally succeeded yesterday to not only unbrick, but also get xiaomi.eu 6.3.24 installed & rooted. I cannot thank you enough Pertti Kosunen for pointing me in the right direction! I realise now why the eu rom was not installing: my partitions were not resized correctly (or "merged" as some people say), the tool I used obviously did not do this in the correct way (Repartition 1.2 GB.zip), so when i tried installing the eu rom...supernova!!! So luckily my Mi3 was only fully soft bricked and not hard bricked, I did not need to open up the phone

I still had ENORMOUS trouble though; First of all I couldn't get the MiFlash drivers installed on the oly PC i could find, an old WinXP Laptop, I was getting "qcCoInstaller.dll not found" errors. Also it had no battery and the mains cable kept falling out and switching off the PC...seriously, I almost went mad!! So when I opened MiFlash anyway, I got a WINUSB.DLL error, which led me to find copies of those 2 files to put in c:\windows\system32 et voilà! Drivers installed and Mi Flash opens fine....total time 48hrs...(screaming kids and lots of Easter chocolate got in the way too!!). From there things became much easier. Mi Flash recognised the phone, and flashing the MIUI China Dev ROM per the instructions in the link above went fine.

I then got a bit stuck on flashing the eu 6.3.24 rom, I installed TWRP via fastboot, then installed the eu .zip rom but got the previously mentioned "failed to mount /data" message and a failed script. This, I now know was because the 2 640Mb system partitions have to be "merged" first (contrary to Pertti Kosunen's comment, this is not done by the chinese dev rom, what I expect he meant is installing the Chinese rom via flashboot will "repair" the partitions, which it did...). Looking through the eu ROM weekly posts I finally discovered I needed to flash the 5.12.17 rom (twice! I did 1st via Updater, 2nd via TWRP after re-fastboot installing it), I then had 1 system partition of 1.2G again. Then I installed the 6.3.24 rom and Super SU and, hey presto, a beautiful new rooted MM MIUI!!

Sorry for the long boring post and the lack of links (I do not have enough experience yet!) but I did want to report back on the experience in case anyone else encountered it