[Android Q&A, Help & Troubleshooting] Teddy Lo:
Hi everybody , today I will share very easy way to unbrick your Lenovo Vibe Shot Z90a40 device .

In my case this device was bricked while instaling custom twrp recovery and custom android 7 OS I got device in that state so the problem was that you are unable to flash your device in diagnostic 9006 mode with to many read only partitions , which I was unable to format or delete in read only state , but actually the problems was not it those partition at all, is about to get

HS-USB QDLoader 9008 mode so you can flash stock firmware on it .

Preparing Steps to do before we start :

1. Disable or remove your Antivirus (because sometimes antivirus can block instaling drivers , ports or running flash tool)

2. Uninstall all the previous drivers you used for flashing or unbrick use free tool called USBDeview

for 32 bit users:

https://www.nirsoft.net/utils/usbdeview.zip

for 64 bit users:

https://www.nirsoft.net/utils/usbdeview-x64.zip

3. Put your windows in Test mode

To put your Windows in test mode just Run As Administrator Command Prompt and insert one of the following command:

bcdedit -set testsigning on ( to enable test mode)

bcdedit -set testsigning off ( to disable test mode)

Or Disable driver signature

for Windows 7

https://www.youtube.com/watch?v=6gYhHD622AA

for Windows 10 users:

https://www.youtube.com/watch?v=71YAIw7_-kg

After that reboot your PC .

4. Uninstall all flash program from your pc like MiFlash , QPST , Qloader ...

Use Revo Uninstaller for advanced uninstaling that clean leftover files and registry which is stored inside your Windows registry.

https://www.revouninstaller.com/revo_uninstaller_free_download.html

After that reboot your PC .

5. Install Microsoft .NET Framework 4 download from here: (if you already have instaled skip this)

https://www.microsoft.com/en-us/download/details.aspx?id=17851

6. Install first right Qualcomn driver download from here :

https://drive.google.com/file/d/0B1Sms71Oe6FIdUE4em9DNjV3Y00/view

Credits for driver : https://www.youtube.com/channel/UC8LoQb68tjBYxwN97b4pvtA

7. Install Lenovo USB driver download from here :

https://lenovousbdriver.com/tutorial/install-lenovo-usb-driver

8. Install Qpst (Qfil flash tool) download from here:

https://drive.google.com/file/d/0B1Sms71Oe6FIVTRwbWpSdEZfM2c/view

9. Install Minimal ADB & Fastboot 1.4.2 command tool download from here

(while you start installing tool check to be in desktop is easy )

https://androidfilehost.com/?fid=745425885120698566

in order to install run ADB & Fastboot 1.4.2.exe with Administrator and just write y and hit enter for all .

10. Download twrp recovery for fastboot flashing and extract to Desktop, download from here :

http://lenovo-forums.ru/applications/core/interface/file/attachment.php?id=56391

11. Download stock firmware for QPST Flashing ( inside is drivers and tools also but don't use that one's ) download from here :

https://cloud.mail.ru/public/HCn4/auVy8DVo1

Also extract stock recovery for later one inside adb folder :)

12. Very important is to use Original usb cable ! otherwise your device won't be recognized property!

13. Make sure your battery is charged if you are not sure put in charger for about 2 hours in charger on in pc!

If your device immediately show up Lenovo logo just hold Vol - and power button together release power button once is rebooting put keep holding Vol - it should be black screen now with white indicator while is charging if not , repeat this proces without charger. This is secure because if you let your phone to be charged with Lenovo logo device will be hot and probably the lcd will hot burning effect !!!

So Let's start :)

1. Make sure your device is OFF first !

2. Hold Vol + and Vol - buttons together in order to enter into FastBoot mode and hold it like that plug usb and see if windows is detecting your device then release buttons.

3. Now once the drivers are successfully installed run Minimal ADB & Fastboot tool .

4. Write command :

fastboot device and press Enter

(you should see your device available )

5. Now write :

fastboot flash recovery (drag inside command tool with mouse "recovery.img" extracted from stock recovery from preparing steps on 11.) and press Enter

6. Next write each command one by one :

fastboot erase cache and press Enter

fastboot erase system and press Enter

7. Now unplug your device from PC.

8. Enter to Lenovo stock recovery by holding 3 buttons :

Vol + & Vol - & Power button at the same time , release just power button once your device vibrate .

Once you see Lenovo MAIN MENU screen press on ''wipeuser data" and wipe each one ,

one by one :

fuse wipe data ( press on YES )

fuse format data ( press on YES )

wipe cache ( press on YES )

Now there is two method for fix :

#First method - Flashing ota firmware from stock recovery

This method is from forum.lenovo.com which doesn't work for me is fail at 49% probably because S208 is old version which is maybe not allowed because I flashed recovery from S363 firmware I don't know but you can try ;) .

1. You need 4 gb or more micro SD card , also make sure is formatted with Fat 32 .

2. Download Z90a40_USR_S208_1507141216_Q2020131.4_ROW_OTAFull.zip, rename it to "update.zip"

https://drive.google.com/file/d/0B8CarqWdS9gZZmJmVGp6NkFWRlk/view

3. Copy it to micro SD card again 4 GB or more !

4. Go into recovery menu:

- turn off the phone

- hold both vol+ and vol- buttons

- power on phone, keep both vol+ and vol- keys pressed until it enters recovery

5. From recovery menu choose install update package

After that go back and press on "poweroff"

#Second method - Flashing stock firmware with Qfil

1. Hold Vol + & Vol - buttons and plug usb cable to enter into fastboot mode and open Minimal ADB & Fastboot to again .

2. Now to put your device in EDL mode and open HS-USB QDLoader 9008 for flashing write this command:

fastboot reboot edl and press Enter

Now you should see that your device is detected like "HS-USB QDLoader 9008" so wait for instalation of that driver.

If you are unable to reboot into EDL mode , flash twrp.img from "twrp/img" folder .

In order to flash twrp recovery probably you need to unlock bootloader , but try first without unlocking if is not flashing then unlock bootloader , if is flashing without unlocked bootloader skip this!

https://www.cyanogenmods.org/forums/topic/unlock-bootloader-android-phone-using-fastboot/

To do that just write :

fastboot flash recovery (drag inside command tool with mouse "twrp.img" from " twrp/img" folder ) and press Enter

3. Once is installed go to QPST directory in my case "C:\QPST\bin" and Run as Administrator "QFIL.exe."

.

Rest you have here here explained :) ...

https://www.gsmhelpful.com/2017/07/how-to-flash-lenovo-vibe-shot-z90a40-with-qfil-flash-tool.html

If for some reasons flashing is fail , plug usb in another usb port USB 2.0 (recommended) and repeat process.

DOWNGRADE from Marshmallow 6.0.1 to Lolipop 5.1

For those one's who want to downgrade device back to Lolipop try this at your own risk !!!

https://forums.lenovo.com/t5/K-and-...-downgrade-to-lollipop-5-1-GUIDE/td-p/3527835

Good luck and God bless you all :)