[Huawei Mediapad M3 Questions & Answers] Samavb:
Mediapad M3 - going back to stock

the reason it didn't work for you is because you have TWRP, Root and unlocked bootloader..

Flashing the zip files through TWRP is 50/50 it might work if you have unlocked bootloader, TWRP but NOT root. ( from my experience)

And also the TWRP version needs to be correct version for it work. For this tablet there aren't many TWRP available. May be 2 or 3.

For installing stock rom successfully through HiCare or firmware finder or even dload or erecovery to work properly you need to have stock ROM, recovery, bootloader locked. These two are important atleast that is what I found in my experience. Otherwise, it will give all these errors and won't finish the process properly. Why?

When you do dload method, it will reboot and it has to update the firmware. If you have TWRP in the place of stock Recovery, then it is acting as a hindrance to its normal process. The situation is same with HiCare too. The tablet has to reboot and update. So all these steps are not completing properly.

Since you have TWRP,Root you can use the greatslon Android 7.0 firmware for your model. The links to that firmware are available in one Russian forum. You can find this easily on google or in greatslon thread in android development section for this device. You can update to that firmware. And then you can use the rollback firmware from Android 7.0 (because this will definitely get you back to Android 6.0 stock) after that you have to update to B009 -> B010 ->B301 this is the path that needs to be followed if you don't want to face any problems. One Italian forum has advised not to do direct update to nougat, they have specifically mentioned to go to nougat in a step by step way. I mean to say if you have B009 then don't update directly to B301. Update to B010 first and then B301. That is their suggestion. I followed their advice and my tablet is working excellently without any issues.

Now to get a stock recovery. You have to use a tool called Huawei update extractor. Extract the recovery from stock update.app and then push it in fastboot mode. For this you can use SRK tools, it is very famous tool for Huawei phones. The same can be used to push adb files from within that software. Why? because your phone /tablet will be recognized in adb without fail. SRK tools is brilliant. Inside that software you need to type 000 to get to command prompt. And then you can use the command "fastboot flash recovery recovery.img" (recovery.img is the stock recovery that you extracted from update.app) I do not recommend doing this. This should be done only if your tablet is bricked/doesn't boot or any other serious problem. Use this option only in that situation or if you know these procedures really well and can handle any consequences. Otherwise, I would advise strongly not to proceed this way. Lot of things can go wrong. That is why I suggested that long procedure to go to Android 7.0 greatslon firmware & then rolling back (Huawei has rollback package).

I hope you understand now why it didnt' work because I faced similar issues with my Huawei mate 8. After performing many experiments and failed attempts I finally understood how Huawei phones/tablets work at least to some extent if not all. That is why I am trying to help everyone so that you all can save your time and don't have to face that unnecessary tension. I cannot ask any one of you to follow my steps. But if you want to have smooth update process then please follow the steps.

I have mentioned detailed steps in other posts. Please check my other posts in this thread and in other threads. This tablet is a beast & at least till your warranty expires I would advise you to stay on Stock ROM. It is stable, you have option to update and it works really well especially B301. I am reading lot of complaints about B302 and would strongly advise not to proceed with that update if you do not know this already. You can update till B301. I can confidently say about that firmware as I am using it daily.

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