Using Reset Button
RouterBOARD devices are fitted with a reset button which has several functions:
Loading the backup RouterBOOT loader
Hold this button before applying power, and release it after three seconds since powering, to load the backup boot loader. This might be necessary if the device is not operating because of a failed RouterBOOT upgrade. When you have started the device with the backup loader, you can either set RouterOS to force backup loader in the RouterBOARD settings or have a chance to reinstall the failed RouterBOOT from a “.fwf” file (total of 3 seconds)
Resetting the RouterOS configuration
Hold this button until the LED light starts flashing, and release the button to reset RouterOS configuration to default.
Enabling CAPs mode
To connect this device to a wireless network managed by CAPsMAN, keep holding the button for 5 more seconds, LED turns solid, release now to turn on CAPs mode. It is also possible to enable CAPs mode via the command line, to do so run the command “/system reset-configuration caps-mode=yes”;
Starting the RouterBOARD in Netinstall mode
Or keep holding the button for 5 more seconds until the LED turns off, then release it to make the RouterBOARD look for Netinstall servers. You can also simply keep the button pressed until the device shows up in the Netinstall program on Windows.