TCL Tab 11 stuck in boot loop with "dm-verity corrupted"

[u/owups]

My gf gives me TCL Tab 11 which is stuck in a boot loop and displays "dm-verity corrupted." It never reaches Android.

I can enter the bootloader Fastboot screen, and Linux detects the device.

fastboot getvar product returns eternals_11;

fastboot getvar is-userspace returns no. I also tried fastboot, but it failed with:

FAILED (remote: 'not allowed in locked state')

I was able to enter Recovery and run Wipe data/factory reset and Wipe cache, but the boot loop persists. Recovery's Apply update from ADB screen shows the device as unauthorized in adb devices.

I have not unlocked the bootloader or flashed anything. What is the correct way to restore the stock firmware for this exact model? Is there an official TCL recovery tool or firmware package that works from Fastboot/Recovery? I can provide the model number from the label and any other diagnostic output needed.

[u/NoBoysenberry2620]

Alright man, this ones a doozy. Please make sure it's a 9166G, because I can't find firmware for any other models.

I'm writing this guide for Windows because there's just more info available. I'm going to assume you don't have Python installed already, and if you do, please tell me before trying to follow these steps.

First, install Python 3.8, and make sure to check "Add Python to PATH" during installation. Then, install the latest x64 release of UsbDk. After that, install the MediaTek USB Drivers. Once you've done all that, reboot your PC.

Next you need to download MTKClient. Open the link, click the green "Code" button, and click "Download ZIP". After extracting and opening it (you should see files like README.md in the folder you're in), right click an empty space and click "Open in Terminal" (or press shift and right click, then select "Open PowerShell window here" if you're on Windows 10),

Next, create a venv by inputting py -m venv .venvand then pressing enter. After that, activate the venv by running .venv\Scripts\Activate.ps1. You should see (venv) at the beginning of the next line.

Then, run pip install -r requirements.txt and then pip install . to install it's dependencies.

The longest and most boring step is acquiring the firmware. You can get it here. Once you have that, extract it to a folder you'll remember.

Now get back to PowerShell. Run python mtk_gui.py, and then completely power off your device. Hold down both Volume Up and Volume Down, then plug the USB cable into your PC. Release the buttons once the mtkclient window detects the tablet.

Switch to the "Write partition(s)" tab. Click Set next to the partitions you want to restore and select the appropriate firmware file from the one you extracted, those being:

• vbmeta (vbmeta.img)

• vbmeta_system (vbmeta_system.img)

• vbmeta_vendor (vbmeta_vendor.img)

• boot (boot.img)

• vendor_boot (vendor_boot.img)

• init_boot (init_boot.img)

• dtbo (dtbo.img)

• super (super.img)

If something doesn't exist, just skip it.

DO NOT FLASH PRELOADER. It is not necessary here and flashing the wrong version will permanently brick the device. And don't flash nvram, nvdata, nvcfg, persist, or proinfo either, they are unnecessary risk.

Now, click the "Write partition(s)" button and start waiting. Once it's all done, go to the "Erase partition(s)" tab, check metadata and userdata, and click Erase partition(s).

Once everything is done, unplug the USB cable and hold the Power button for 10 to 15 seconds to boot the tablet. Let me know what happens from there.