Install Dumber OS yourself on a compatible device
It is of utmost importance you do a backup before attempting this process. It is very easy to completely and irreversibly brick your device - even we cannot save them when this happens! DO NOT ATTEMPT THIS WITHOUT A BACKUP.
Already have one of the supported phones and want to install Dumber OS for free? Follow this guide. If you run into any trouble, pop in on the Duoqin Discord channel. Note that this is a very technical process, so make sure you are comfortable with the command line before attempting this.
Download Dumber OS
Download from Github. Builds updated on December 23, 2025. Make sure to unpack first!
Necessary tools
Make a backup
It is of utmost importance to back up the original software on your phone. This way if anything goes wrong, you can easily go back and start from scratch. You’ll need about 5 GB of free space on your hard drive. Without this, you risk permanently bricking your device.
mkdir stock_rom
mtk rl --skip userdata f21_stock_rom
Unlock the bootloader
This will factory reset your phone!
Unlock developer options in the phone by tapping five times on the build number in Settings->About phone. Go into Settings->System->Developer options and enable 'USB debugging' and 'OEM unlock'. Connect to the phone through ADB and issue the command:
adb reboot bootloader
You should see the text "fastboot" at the bottom of the phone's screen.Now run:
fastboot flashing unlock
This will unlock the bootloader, you might have to confirm it in some way. Make sure the step is successful. Afterwards run:
fastboot reboot fastboot
You should see a screen with "fastbootd" at the top in blue or red letters.
Flash the new system
Erase user data if you are upgrading from the stock ROM. Updating Dumber OS doesn’t require this step.
fastboot erase userdata
fastboot erase metadata
Flash Dumber OS. Make sure you unpack the zip archive first!!!
fastboot flash system dumberos_???.img # replace ??? with the actual filename
If you get errors that the system partition doesn’t exist, make sure that you are in the proper fastboot mode (use the ‘adb reboot fastboot’ command or enter fastboot mode from recovery). You should see “Fastbootd” written at the top of the screen on the phone.
If you get errors that the system partition is too small or can’t be resized, try flashing the vanilla Dumber OS and switch to g-apps afterwards through Settings->System->Updates.
fastboot reboot
Booting the system for the first time might take 5-10 minutes.
Recover from backup
mtk wl stock_rom
6 comments
Amazing firmware, thank you. Different apps use different scaling methods. So for Qin F21 Pro users I recommend these display settings: Font = 0+2, Scale = Maximum.
Qin F21 Pro users without volume keys, instead of going to fastboot to unlock bootloader, use:
mtk da seccfg unlock
Otherwise you won’t be able to confirm unlocking without volume keys. If you stuck at that page, hold power button (end call) for 15+ seconds.
Shuka: we might do it some time, but we are focused on improving the ROM and running our shop right now. You can get a lot of help on the Discord channel linked above.
Macz: fixed, thanks!
Johannes: No idea, give it a try! Though remember to always make a backup of the stock firmware.
Would be great if you guys make video tutorial of this process
ROM Links broken, can you fix please ?