I have a super Xiaomi Router, which has broken due to an update. If I connect a USB TTL device, the recovery interface is unavailable. I'm not a serviceman, I don't know how to fix it.
How can I reprogram the flash memory?
Has anyone done this before?
fwiw, if there is no working serial access, there's probably no chance of recovering the router, unless you use a spi flash programmer to copy the ROM from another identical working R3G, to see whether that may fix the problem?
If the bootloader still works (text is issued from the serial port as it attempts to boot), use it to restore to stock firmware then redo the OpenWrt installation from the beginning. As shipped, the bootloader has no bootdelay which means you can't use serial to interrupt the boot and restore. The bootloader can be patched but that is best done from a running OpenWrt.
I don't know about the Russian parts it might be about the V1 which has a NAND chip. If you have a V2 it's a NOR chip and that would not apply.
I have the 4A Gigabit version. One problem with Xiaomi is their model names can be ambiguous.
Did you say you get a bunch of text about the memory and the kernel and stuff like that scrolling out of the serial port when you turn it on? That means the bootloader is running, which is a good sign. There is probably no way to stop or interact with it though. If it says "Autobooting in X seconds" where X is not 0, try hitting return at exactly that time.
Can you use something like PuTTY and capture all the boot messages from serial TTL connection when you turn on the R3G, and post here? Any bootloader messages will only appear for a split second under normal circumstances.
You failed to mention 'how' you bricked the R3G despite repeated requests.
As suggested by @mk24, the bootloader may be undamaged. Therefore you may not actually need to replace the bootloader etc.
Unless I'm mistaken, I believe all the instructions you found to install a new bootloader and other firmwares, assumes the original Xiaomi bootloader is working to allow TFTP to function, to be able to install the new files!
It's stock Xiaomi firmware. I think you should write MTD1-Bootloader.bin partition in first 512KB of flash memory or use MTD0-ALL.bin to overwrite all space in the chip and then get back to OpenWRT.