RB760iGS ROS7.3.1/FW7.3.1 Failed to boot (x2)

Hardware MikroTik hardware general
1

I have quite a few RB760iGS “hEX S” used as Fiber CPE/Routers. Last night, while updating one it failed to come up. I pulled a replacement off the shelf and upgraded it and it also stopped booting.

I was able to boot them via Netinstall/Netboot and they “Format Hard Drive” then during the Netinstall transfer they fail and stop responding.

I tried to Netinstall v7.1.3, v6.49.6 and v 6.48.6 but couldn’t get a successful transfer. Eventually they stopped beeping at startup, and while the SFP light sequences to indicate NetBoot (Solid > Blinking > Solid > Off) they no longer show up in NetInstall.

I have tried powering with both PoE (24v Passive) and the included wall wart.
Any ideas?

2

I was able to recover both boards using the backup bootloader v6.46.3 with Netinstall v6.48.6 to install RouterOS 7.3.1

The RB760iGS boards would boot from Netinstall 7.3.1 but it was never able to copy firmware. I jerry-rigged a serial connection and got

transfer started *******[lots more stars, no dots]******* transfer timed out  falling back to small packet size**************

Then fail and reboot.

To get a reliable ethernetboot I had to:

  • Remove all ethernet cables
  • Hold Reset
  • Plug in power
  • Wait for SFP LED Blink, then Solid
  • Plug ethernet to etherboot port (port 1 on the hEX S)
  • Wait for SFP LED Off
  • Release Reset button

Got a beep and boot every time.

3

I have done this, but the SFP light doesnt even come on.
the power light is on, my pc sees that theres a network device connected via port 1
holding the reset button does nothing no matter how long i hod it in.

4

Make sure you have dumb switch between PC and RB, so PC network interface doesn’t come up/down/up/down… during RB reboots. If it does, it can miss the time window to initiate netinstall procedure, because especially newer windows versions are super slow to bring up the interface.