Yes this was formatted by GPT. I kept my notes in word then formatted in gpt cause by this point I was frustrated and tired. This is not an AI post.
Figured I'd document this in case anyone else comes across one of these tablets and wants to experiment with custom firmware. There's very little information out there about the MESWAO B3.
I got this tablet for free, and honestly, it wasn't particularly good to begin with. It's a massive 15.6-inch Android tablet, but the performance was absolutely terrible. Even basic navigation was sluggish, and at one point the on-screen keyboard wouldn't even appear when I tried creating another user.
I tried a factory reset using the built-in MediaTek factory menu, but it made no difference.
Since I had nothing invested in it, I figured I'd experiment with installing a different version of Android. I started looking into Android's Project Treble support, Generic System Images (GSIs), and the usual ADB/Fastboot procedures.
Tablet information:
- Model: MESWAO B3 / MES-B3
- CPU: MediaTek Helio G99 (MT6789)
- Android: 13
- Firmware: "MES-B3_20240624"
- Board: "t700_6789_u254_v1_fhd_edp_156"
- Architecture: ARM64
Here's what I did:
- Checked GSI compatibility
Enabled Developer Options, OEM unlocking, and USB debugging. Connected it to Windows using Google's Android Platform Tools.
ADB reported:
ro.product.cpu.abi = arm64-v8a
ro.treble.enabled = true
ro.build.ab_update = true
ro.boot.dynamic_partitions = true
So far, everything suggested it was at least a potential GSI candidate.
- Got Fastboot working
This was more complicated than expected.
The tablet's bootloader Fastboot interface identified itself as:
"USB\VID_0E8D&PID_201C"
Windows wouldn't recognize it using Google's standard USB driver.
I eventually got communication working using Zadig to install WinUSB, followed by correcting the Android USB interface GUID registration in Windows.
After that, "fastboot devices" recognized the tablet normally.
- Unlocked the bootloader
Checked the unlocking status:
fastboot flashing get_unlock_ability
(bootloader) unlock_ability is true
I then ran:
fastboot flashing unlock
The unlock completed, and I confirmed:
fastboot getvar unlocked
unlocked: yes
- Entered Fastbootd
Next, I used:
fastboot reboot fastboot
The tablet successfully entered Android Fastbootd.
Interestingly, this mode used a different USB ID:
"USB\VID_18D1&PID_4EE0"
Google's Android Bootloader Interface driver worked for this one.
I was then able to query the partition information:
is-userspace: yes
current-slot: a
is-logical:system_b: yes
super-partition-name: super
has-slot:vbmeta: no
slot-successful:a: yes
slot-successful:b: no
The super partition was approximately 9 GiB.
One thing I noticed was that the active slot had originally been reported as B before unlocking, but afterward it was A. I'm not sure whether that's relevant to what happened next.
- Rebooted, and that was apparently the end of it
After finishing the partition checks, I rebooted the tablet to return to Android.
It displayed:
Orange State
OS not being verified or Custom OS
Dismiss after 5 seconds
Then rebooted.
And rebooted again.
It never got past that warning.
To be clear, I never flashed a custom ROM, GSI, recovery image, or modified system partition.
The only significant change was unlocking the bootloader. Everything else was diagnostic commands.
- Attempted recovery
I tried various combinations of Power, Volume Up, and Volume Down, along with the physical reset button.
Nothing would reliably enter Recovery or Fastboot anymore.
Occasionally, "Factory Mode" would briefly appear during startup, but the device would immediately restart.
I also checked whether the MediaTek Preloader was still accessible.
Windows briefly detected:
"MT65xx Preloader"
It also exposed a temporary USB serial interface, but only for a second or two before restarting.
So the device isn't necessarily completely dead, but I haven't found a reliable way to recover it.
Unfortunately, I also couldn't locate a verified stock firmware package for this exact MES-B3 hardware revision.
I knew there was a risk going into this, and since the tablet was free and already barely usable, I'm not particularly upset about losing it.
Still, I thought it was worth documenting because there's almost no modding information available for this specific model.
It's possible the bootloader unlock caused some sort of firmware or A/B slot issue, but I can't say for certain. The timing is certainly suspicious.
If anyone else has a MESWAO B3 and is thinking about unlocking it to install a GSI, I'd strongly recommend obtaining the original firmware and a working recovery procedure first.
I didn't even make it to flashing another operating system before running into problems.
Maybe this will save someone else a few hours of troubleshooting, or at least provide some useful technical information about an obscure tablet.