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 192.168.31.100 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! 
Ok. I start again.
The router is mine. Long time ago I installed openwrt 19.07 on it.
Today I take it again. I would like to upgrade it, but brick the router.
So I try to debrick it.
With your help it is done.
It is now with the originel firmware of xiaomi.
I do not manage to link it in xiaomi app, therefore i can not have ths ssh password.
So In the openwrt help, it says we can install it via uart.
But it does not work. When I write setenv uart-en 1, and setenv ssh_en 1 saveenc. Then I write boot, and normally in the uart console I should have have the prompt after restart but it is not the case.
So now mk24 try to help me.
But I do not fin snapshots initramfs for xiaomi 3g
And the command line tftpboot 0x81000000 XXX.bin do not work for me...
Thank you
You should be in U-Boot, so this is confusing me.
Are you saying you restored Xaomi instead of OpenWrt?
All you have to do is:
- TFTP boot OpenWrt
- Login
- Sysupgrade
???
Is this U-Boot???
Do you still have your TFTP server connected?
TFTP fails again???
Provide more information.
yes i m back to xiaomi firmware.
But i have access to uart serial console.
And yes the tftp do not work again. but thisbtime i have plugged rj 45 cable and set ip adress to 192.168.31.100 fotbthe server like the firstctimebitbwokrs.
So what can I do to install openwrt ? step by step please.
Thank you.
and what do you call uboot ? uart console ?
Please re-read the i would like to follow the steps but I don t understand it.
what is uboot ??
what means * TFTP boot OpenWrt ?
thank you
???
Do you recall when you first made your post?
The exact same location...this is U-Boot - the bootloader.
If we say TFTP, you can be sure you need to be in U-Boot again and set it up your TFTP server in Windows again. This is not gonna change, so no need to be lost again - we'll be referencing the same place.
You really need to understand that menu and get there.
It's been a while since I've done this so I'm not sure that's the right syntax of the tftpboot command. Once you have the prompt from option 4 try help tftpboot
If you have the Mi 3G v1 which has a USB port (not the 3G V2 which is very similar to the 4A Gigabit-- neither of those have a USB port), use this file:
https://downloads.openwrt.org/snapshots/targets/ramips/mt7621/openwrt-ramips-mt7621-xiaomi_mi-router-3g-initramfs-kernel.bin
Rename it something short like file.bin on your TFTP server.
Then sysupgrade to a release file like this one (so you will have the web interface):
https://downloads.openwrt.org/releases/22.03.0-rc1/targets/ramips/mt7621/openwrt-22.03.0-rc1-ramips-mt7621-xiaomi_mi-router-3g-squashfs-sysupgrade.bin
There is an intramfs-kernel file in the release directory which could also be used for the TFTP to RAM boot.
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Paste the Sysupgrade file for the OP too, please - if you're on the page you referenced.
We assume you want OpenWrt and not Xaomi. You accidentally re-flashed Xaomi?
We are simply telling you how to follow the instructions to boot OpenWrt and flash it back once it's running - but you seem to get confused when we suggest you want OpenWrt.
Do you want OpenWrt?
If so, you would tftpboot the OpenWrt *.bin file - not Xaomi.
ok. it seems to be better.
yes i want to instl openwrt
I ll make a new try later this day.
Thank you. I know it s borrig to take time to explain.
So i try again, but i can t transfer the initramfs file...
always timeout error.
I put this file in tftp directory on myvlaptop.
Serup my ip adress as 192.168.31.100.
I launch the uart cpnsole, choose option 4.
write tftpboot 0x81000000 ramfs.bin
it says our ip is 192.168.31.1, server 192.168.31.100...
I plug a rj45 cable in the blue port of xiaomi router to a switch.
and plug an another cable from the switch to my laptop...
what do i do wrong ?
Yes, now I manage to transfer the ramfs file.
I see openwrt is strating when I boot the router.
With ip scanner, I see the router takes IP 192.168.1.195, but impossible to reach the adress with firefox or chrome !!!
More weird, connectin with uart on the router, I can ping itself (192.168.1.195) and my laptop configure at 192.168.1.36 is responding.
But If I go on my laptop, 192.168.1.36 is responding, but not 192.168.1.195 !!!
Ip scanner sees it anyway ...
Thank you very to all of you.
I finally managed to reinstalled a working version of openwrt.
Option 4 was not working for transfering the file.
I gave a try to option 1, and it worked.
Last question. By default the interface adress of openwrt is 192.168.1.1. I would like to change it for 192.168.1.97, but it doesn't not work. If I change it in network/interface, it takes time. I can never naviagte to 192.168.1.97.
Then a few minutes later, the interface can be access with 192.168.1.1 again !!!
Thank you
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