Rooting my Lenovo Smart Tab M8
For my first post, I simply wanted to share an interesting thing I did. Today, I rooted my Android tablet and it wasn’t the first time. This Lenovo tablet is quite simple. The processer can be slow and not much works on it beyond watching things. It’s pretty good for watching things but it’s certainly not the best screen I’ve ever seen. What some may find interesting is the Dolby Atmos equalizer which is simply an application which changes some EQ, as least that’s what it sounds like, to match what you’re currently using your tablet for. Like, changing it to dynamic or music mode. I assume it’s doing something but maybe it’s just a simple way to attract more people to buy it because the assume the speakers will be quality. They’re fine in reality. It comes with a stand which charges via micro USB. The few times I do remember using it, it was for simple stuff like playing a game through Parsec or watching a movie.
It still has a micro SD slot, runs Android 10 and never recieved any other updates beyond last year. The most interesting thing it can do is easily be rooted. I did this exact process a while back but after experimenting with something I ended up bootlooping it and fixing it through the Lenovo Rescue application on Windows, which is actually what can help you get into rooting the device to begin with.
I remember that I was following the process via a Reddit post but that must be gone now because not much talk is happening on Reddit about this tablet and I can’t find the original post, nor did I save it. I’m sure by now many people have returned this thing or recieved a newer tablet but I still kept using it, not to mention that on XDA, it appears people were still using some variant of this device in 2023 so it wouldn’t be stretch to say someone other than me is currently still using it.
In case you’re following along, back up anything you want to save. The device will become erased once rooted.
It’s pretty easy to root it. You simply follow the same steps as you would if you used Magisk on any device, although I have only used it on this device so I’m not sure about that. What I’m talking about really is the steps provided on the Magisk website.
To download the firmware for this tablet and I presume for any other, you can use the Rescue and Smart Assistant application for Windows only. Then, plug your device in after signing in and setting up the application and install the companion applicaton on the device, go over to the recovery tab and download the .zip firmware that is listed. Hit the Windows Key and R to open the run dialog then go to C:\ProgramData\RSA folder and extract the files from the relevant folders.
Afterward, you really only need the boot.img and vbmeta.img, although you can keep the entire downloaded archive in case of any problems. Download both files and download Magisk on the device itself. Send your boot file to the tablet through any means, even through ADB, and use Magisk to patch the file by selecting install on the Magisk section then selecting your file. Afterwards, on the device should be a Magisk file that’s been patched. Transfer this to your computer. Finally, on your Mac, install adb/android-platform-tools with homebrew or download Platform Tools as a zip and use the individual executables on Windows.
Now it’s time to use Fastboot. Type in the command adb reboot bootloader and then flashboot flashing unlock which will prompt you on the tablet to push volume up. Afterward, you can use flashboot flash boot your_file.img afterwards you can use the vbmeta.img file from the firmware zip and do the exact process for that file except with this command fastboot flash vbmeta --disable-verity --disable-verification vbmeta.img which will finally allow the device to be rooted. Now, simply type fastboot reboot and once you boot again and set the tablet back up, you’ll see Magisk in the list of apps. In my case, for some reason, I had to reinstall the app. Normally, I would assume it didn’t work but it did just fine. Using adb shell and then typing su brought up a prompt for root access like as if it was a native app on Android and clearly meant the device was rooted.
Update 7/12: Originally, I just ended it there. However, with some more research I found you can use a “GSI” or Generic System Image with this device. Effectively updating it to keep it more performant and private if you want. These GSIs are not perfect but they do exactly what I need them to. Run LineageOS and that is it. I plan to work on a custom ROM for this device. I want to make it more like a tablet ROM since there are some minor things which definitely don’t work for a tablet like vibration settings and phone applications. These are included by default so they can work on a wide range of devices. The issue is I am not too familar with making a full custom ROM. I do recognize there are other versions which allows for connectivity through SIM but those are probably not everywhere. Plus, my device doesn’t have a SIM.
If you want to get started, go to the Treble Experimentations GitHub wiki and then decide what version of Android you want. If I do end up making a custom ROM, I will probably base it off of 14 even if I’m on 13 right now. After choosing, go to “Unoffical Android (insert number here)” and choose download where it says “LineageOS” by AndyYan. From here, you can have the option of “bvS” or “bgS” or preferably “boS” which are all different even if they sound similar. The B and S parts of these images are A/B which is supported by the tablet and S being Superuser (although it could mean something else). The first option is vanilla. This just means no Google Apps. You can get apps through F-Droid or other means. Second is Google Apps. This will install a set of Google Apps but I don’t know which. Google Apps can also just slow down things and even Lenovo used the last option, that being Android Go. Now, this isn’t the Android Go operating system which I think exists, instead, it just provides Android Go applications which are known for being lighter for light systems. If you need Google app support or something can only be used through the Play Store, this is your best best. Not to mention, you’re not likely to even use these Google apps if all you need is the Play Store.
That’s it. Make sure your file isn’t a64 or vndklite and you can flash the GSI on your device. Simply go into fastboot with adb bootloader reload (turn on USB debugging first though) and then fastboot flash --disable-verification --disable-verity vbmeta finally leading to fastboot flash system my-lineage-file.img which will get the new OS installed. Now just fastboot erase userdata and fastboot reboot to see your new OS. It’s pretty cool but as already mentioned, awkward due to a few phone related features.
One of the biggest issues I had was using headphones. Login to your device thorugh adb using adb shell type su then input the command setprop persist.sys.overlay.devinputjack true and restart. If you don’t have root access when you try to use su, keep restarting. The Magisk app was given to me after a few restarts had taken place. It’s going to say there’s a few errors with your binary or whatever but these can be ignored as root access does work for when you need. You can also complete this process using Termux.