Hello.

I have a RB2011UAS-2HnD-IN unit that is stuck at "starting kernel" after an overclocking attempt. Unfortunately, I do not have the Cisco-style serial console cable to reset CPU speed in the RouterBOOT menu, and I do not have the configuration backups (which would allow me to reformat NAND and reinstall from scratch).

Is there a way to reset CPU speed temporarily or at least retrieve the current configuration somehow? Netinstall works, but there is no way to backup existing configuration or partially edit it (there are only options to "keep old configuration" or "reset everything").

OK, I solved this myself by pure luck.

For anyone interested: forcing backup bootloader did the trick. According to RB2011 manual, to force the backup bootloader, you need to hold the RESET button while powering up the device (and release it shortly after you see "routerboot configuration" on the LCD, to avoid actually resetting your configuration). This allowed me to boot existing RouterOS installation and set the CPU frequency back to nominal.

By extension, I suppose that this method allows to skip any incorrect RouterBOOT configuration.