Getting the Dumber Mini black screen fix to actually run

October 01, 2026 by Timo Furrer

Dumber ships a fix for the black screen defect as a Windows .exe. Unfortunately there's nothing for Linux, so I had to get hold of a Windows laptop first. It didn't work for me out of the box. It crashed first, and once that was fixed it never found the phone.

What the .exe does

The .exe is a self-extractor. It unpacks MediaTek's SP Flash Tool, the firmware images and a batch file into %TEMP% and runs this:

@echo off
SP_Flash_Tool_V5\SP_Flash_Tool_V5\SP_Flash_Tool_V5\flash_tool.exe -s DumberOS_V06_20260810\A671_01H_H281C_Dumber_mini_V06_08-09-2026_1136\MT6761_Android_scatter.txt -c download -d DumberOS_V06_20260810\A671_01H_H281C_Dumber_mini_V06_08-09-2026_1136\MTK_AllInOne_DA_MT6761_H281C_2444.bin -a DumberOS_V06_20260810\A671_01H_H281C_Dumber_mini_V06_08-09-2026_1136\auth_sv5.auth
echo Flashing complete!
pause

It flashes the preloader, lk, boot, dtbo, tee, vbmeta, the modem and a few firmware blobs to slot a. It does not touch super or userdata, so DumberOS and your data stay as is.

Note the last two lines: Flashing complete! is printed no matter what flash_tool.exe did. Ignore it and read the output above it.

Crash: "To create SP Flash Tool logs path fails!"

On the first run it died with an assertion in flashtool\Logger\Logger.cpp, line 433. The bundled option.ini contains:

[Trace]
LogPath=D:\\ProgramData\\SP_FT_Logs

So it wants to write logs to D:. My laptop has no D: drive. Map a folder to D: before running the .exe:

mkdir C:\fake-d
subst D: C:\fake-d

Remove it again with subst D: /d when you're done.

No phone found: S_TIMEOUT

Next it waited at Search usb, timeout set as 120000 ms and gave up after two minutes:

SearchUSBPortPool failed!
Failed to find USB port
Connect BROM failed: S_TIMEOUT(1042)

Meanwhile the phone just went into its charging screen. The MediaTek USB driver was missing, so Windows never offered the port the tool looks for.

The driver is on the Microsoft Update Catalog. Search for MediaTek PreLoader USB VCOM and download a recent package for your Windows version. It's a .cab. It has subfolders with files of the same name, which Explorer doesn't show, so don't copy the files out by hand. Extract and install it from an admin command prompt:

mkdir C:\mtk-driver
tar -xf C:\Users\you\Downloads\driver.cab -C C:\mtk-driver
pnputil /add-driver C:\mtk-driver\*.inf /subdirs /install

To check it, open Device Manager, enable View > Show hidden devices and plug in the powered-off phone. A MediaTek PreLoader USB VCOM (Android) port should show up under Ports (COM & LPT) for a second or two.

Running it

Before running it, I backed up every partition it writes from the phone with adb root and dd. The .exe doesn't make a backup itself, which I would have expected from a tool that overwrites the preloader.

Start the .exe, wait for Search usb, timeout set as 120000 ms, then plug in the powered-off phone. With the D: drive and the driver in place it flashed fine.

Conclusion

So far the fix actually works for me. No black screen since.

Still, I have little trust in what that .exe does. It crashes on a hardcoded D: path, doesn't tell you it needs a driver and reports success when nothing happened. If basic things like that don't work, I wonder what else wasn't tested.