Please let me know if this works for you and if you have any issues, please also read and follow the guidelines carefully as there are lots of things like using all the applications as an administator and changing directories that are important.
I am also looking for a way to install TWRP or another recovery thing on this device so I don't brick it, as I want to root the tablet and muck around with it. Has anyone got any experience of doing this successfully and does anyone have links to methods to create a cloned backup of the standard OS?
This was done on a brand new Mediapad M3 Lite 8 (the Wifi version, not LTE) with Android 7.0, EMUI 5.1, CPN-W09, build CPN-W09C100B251 - BUT will probably work on the LTE version, the non-lite version and the 7 and 10 inch models.
IMPORTANT: This costs money and is done through the DC Unlocker tool, it costs 4 credits (4 euros/dollars) for the Mediapad M3 Lite 8 (Wifi, not LTE) as Huawei now do not offer the bootloader code AT ALL . I have copied/streamlined the steps below that were found as guides originally at the dc unlocker website, check their site guides to find originals.
Step 1 - Developer Options enable
Go to settings, about tablet, tap build number 7 times to unlock developer options
Go to developer options, enable OEM unlock, enable USB debugging
Step 2 - Enable manufacture mode
If your phone has a dialpad, enter dial pad code *#*#2846579#*#*
IF your phone doesn't have a dialpad, go to calculator and enter ()()2846579()()=
This willl take you to a developer menu, select "Project Menu", "Background settings", "USB ports settings", "Manufacture mode".
Step 3 - Install drivers
Connect your Android device to your PC with a usb cable and either install Hisuite from the connected drive that will attach, or download it from the Huawei website by searching for Huawei Hisuite and going to their official website.
To check this has worked, go to Device Manager on your PC and look for Modems - there should be an entry called Android Adapter Modem - if this is not present try disconnecting/reconnecting your device and restarting Hisuite.
Step 4 - Read bootloader code
Download the latest DC Unlocker tool from dc-unlocker dot com and extract it, then AS AN ADMINISTRATOR (right click and Run as Administrator) run the client.exe (was called dc-unlockerclient2.exe)
Click Select Manufacturer dropdown and change to Huawei Phones, not Modems, press the magnifier/search icon at bottom left and your phone info should be found. This should also
Step 5 - Buy credits from the dc unlocker site as a new user, try 4 credits first and then login with these new user details in the dc unlocker application on your PC, this will show your credits and the phone connected as well as the cost. Click the Unlocking icon on the top right and click Read botloader code to get your code. Make a note of this/copy it somewhere.
Step 6 - Go back to the folder that dc unlocker is in
Go into the unzipped folder and then copy the location of this folder by clicking on the address bar in File Explorer and copying this location, you'll have something similar to
Step 7 - Turn off your phone and turn it back on holding the Vol down and Power buttons to enter fastboot mode, connect your device to your PC
Step 8 - Open cmd by searching for cmd in windows, right click cmd and open it as administrator, you'll get the black and white windows terminal
In the terminal type "cd C:\Users\ExampleUser\Downloads\dc-unlocker2client_1.00.1403" (or the path for the latest version of the dc unlocker you have downloaded) without the quotation marks and with YOUR directory path as described above. The command cd just changes directory to the one you give. Your terminal should now show the above directory as the path in which it now sends commands, i.e the > mark is now displayed after the directory path we copied
Step 9 - Type "adb devices" without quotation marks to start the adb daemon
Step 10 - Type "fastboot devices" without quotation marks and you should see a device number with the word fastboot next to it.
Step 11 - Now type "fastboot oem unlock" without the quotation marks, followed by a space and then your bootloader unlock code i.e
fastboot oem unlock XYZ123456789
Step 12 - Your device should show a screen asking you to accept the unlock, then onto another screen where you should press the power key to continue onto booting your factory reset unlocked device.
Step 13 - You might have to disconnect the USB cable and reboot your device now, and you'll set up the device from scratch again - but now the bootloader unlocked, allowing you to load stuff like TWRP if you can find the right version - which I can't right now!