Mi3g brick ... try to transfer kernel0.bin


today I wanted to use my mi 3G v1 router again.
Openwrt 19.07 was installed. I try to upgrade, but to router brick...

So I want to recover with uart /usb.

I plug all the things.
I use putty to connect via com 7.
I see the booting process and press 2.
It ask me ip adress for router ( then for tftp server (
then the name of file to transfer : kernel0.bin.

I then press enter, but it writes loading : T T T ..
And few seconds later it says timeout.

In fact I don't know how to setup the computer and what to do with the kernel0.bin file I downloaded.

I try to use TFTP_server, but I don't know how to use it.
I put the kernel0.bin file in programmdata/winagents/tftp_server/

But it do not work.

Can some one take 5 minutes to explain me how to do ?

PS : I unplug my computer from internet. I put a manual ip adress But still same error.

Thank you.

And I assume you're following the instruction on the device page, correct?

thank you for the link.

It doesn t work either...

On the laptop, i disable the wifi. and disconnect rj45 cable.
I set manual ip adress

I connect the mi wifi 3g router with usb cable on tx rx gnd.

With putty I connect to the router via com7 (115200 bauds)
I see things loading... I choose number 2 (load system code then weite to flash via tftp)

I set ip adtess router to
tftp server to
and the write kernel0.bin (file to transfer.)

it does nothing exect writing T s on the line and then timeout error
What I am sping wrong ?

thnk you

"And I assume you're following the instruction on the device page, correct?"

What do you mean ?

Please provide the link to the instructions you're following.

section debricking using serial connection.

But I would like a walkthrough to send kernel.bin file. I dont know how to do it.

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The page provide no TFTP information, so I assume what you described is on the screen when you connected via PuTTY:

  • Make sure your laptop or PC's firewall is turned off
  • Make sure the connection does not drop before transfer

Hope this helps.

win 11 firewall is desactivated.

Don t know what to do more...

And yes what i describe is with putty connection

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Which are you using to transfer, Ethernet or WiFi?

What ?

neither of them...

The file must be transfered with the serial connection, no ?

If not I don't know what to wired on the router.

Or do you mean I need to connect rj45 on the router and on the laptop to a switch ?

Ummmm, do you recall telling me you set IP addresses?

The instructions say use TFTP. TFTP works over an IP network.



Well, now we know why it wasn't working...enable your Ethernet and try again.

So I need to connect the router and my laptop on a switch !!!

If for some reason you're unable to simply connect them directly to each other, then yes.

thank you very much.

I really tought the uart connection emulated a tcp connection. So I unpluged all network connection...of course it was not working.

Now I manage to transfer the kernel file, and manage the install the firmware.

Tomorrow I could install openwrt again...

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Now, i've got a new problem :
I managed to install the router, but I can't install it in xiaomi home application.
So my router is not linked to my account and therefore I do not have access to root password in my xiaomi account.

So I can't install openwrt on it !!!!

How do I do ?

Thank you

Since you have control of the uboot console (someone must have done the bootdelay patch) you don't have to go through stock firmware. RAM boot the initramfs OpenWrt and use it to install the sysupgrade. That is done by getting a console prompt using option 4. Have the initramfs firmware (from the snapshots directory) on your TFTP server.
tftpboot 0x81000000 file.bin
The file will transfer. Nothing is changed in the flash, the file stays in RAM.
bootm 0x81000000
OpenWrt will start. This is a version running in RAM that will be erased on the next reboot. So you next need to scp the sysupgrade OpenWrt (a release version) to the /tmp directory and use the sysupgrade command to install it to flash.

wow !!

Slowly please. I don't all understand.

On the openwrt website, i don't find any snapshot for xiaomi router 3g ...
I find kernel, kernel 1 rootfs and sysupgrade

Then where do I write this ??? tftpboot 0x81000000 file.bin

Sorry, but I have to understand wht I have to do.

Thank you.

PS : I try something.

I plug my laptop and the Xiaomi router on a switch with rj45 cable. Set ip adress to for the laptop.
Put the file
ifound openwrt ramips for 7621.bin in the directory to be transfer. I rename it kernel.bin
With option 4, when
i write tftpboot 0x81000000 kernel.bin, nothing happens, the file is not transfering !!!!

Fu###ng xiaomi router !!! Why can't I just have the ssh password !!! Just have to link the router in xiaomi app but it fails !!! saying it is surely allready linked, but I dissociated it. Now I'm blocked.


You type the command "in the U-Boot...".

@davidmarli - you do understand U-Boot is the bootloader of your device, correct?

You're gonna have to take a little responsibility in understanding an embedded device here to proceed.

You didn't read.

He says me option 4 not 2 ...

I don't understand.

I'mma try one more time.

You are off the instructions, you are being given a command to boot OpenWrt - you simply have to calm down and lean to TFTP just like before and boot it.

Someone already got access, you're past that! :point_left: