MikroTik RB750r2: repair via UART

Colleagues, please tell me what I can do in my situation.

I installed OpenWRT on MicroTik RB750r2. I have installed OpenWRT on routers of this model several times this way, and everything was fine.
This time it all started well. I downloaded the system via DHCP and flashed the upgrade file. (openwrt-18.06.2-ar71xx-mikrotik-rb-nor-flash-16M-initramfs-kernel.bin & openwrt-18.06.2-ar71xx-mikrotik-rb-nor-flash-16M-squashfs-sysupgrade.bin)

Then I installed the localization and several programs (mc, openvpn-ssl).
After that, I rebooted the system.
At the router all the LEDs went out and he stopped responding to the connections.

Making sure that everything is bad, I opened the case and soldered the connector to the built-in UART. Then I connected a TTL-serial cable to it.

Under normal boot, the terminal is silent.
If I boot up with the 'Reset' button pressed and hold it until the right led starts blinking - UART writes:


OpenWrt kernel loader for AR7XXX/AR9XXX
Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
Decompressing kernel... done!
Starting kernel at

and remains in this position without any timeout.

What can this mean?
Is there a way to boot the system with TFTP in this bootloader?


Yes. That is the procedure most extensively documented in the Wiki. In fact, this is the common method for installing on MicroTiks.


Once booted, you then simply flash using normal OpenWrt sysupgrade procedures.

I believe that you have not read my entire message.
I just installed the system.
After rebooting, it does not see the network.
I brought the message of bootloader. Can I boot over the network with it?

I read that.

  • Please verify which flash procedure you used
    • Flash u-boot (optional); or
    • Boot over ethernet (using DHCP PXE)
  • Are you saying there's a bug in the documentation or procedure?
  • Does that mean you cannot ping, SSH, what?

I'll answer this too - it means that you booted a recovery partition. It's probably not configured properly for one that's OpenWrt.


Please see the WIki for instructions on how to boot over the network: