The examples on factory reset has been ctrl+shift, ctrl+shift+6,
delete, escape and ofc normal break command.
It's not actually a factory reset; it is a password recovery. Once you get that done, you can then wipe the configuration. Use the Break for your terminal application. To perform a password recovery:
From the Cisco NCS 520 Series Router Configuration Guide, Cisco IOS XE 17:
Make sure that the hyperterminal has the following settings:
9600 baud rate
8 data bits
1 stop bit
No flow control
Use the power switch to turn off the router and then turn it on again.
Press Break on the terminal keyboard within 60 seconds of power up to put the router into ROMMON. In some cases Ctrl+Break key
combination can be used.
Type confreg 0x2142 at the ROMMON.
1> confreg 0x2142
The router reboots, but ignores the saved configuration.
The router will reload and prompt for configuration.Type no after each setup question, or press Ctrl-C to skip the initial setup
Type enable at the Router> prompt. You are now in enable mode and should see the Router# prompt.
Reset the config-register from 0x2142 to 0x2102. To do so, type the following: config-register configuration_register_setting Where,
configuration_register_setting is 0x2102. For example,
(config)# config-register 0x2102
Sometimes, it can be difficult to send the Break at just the right time, and you must try it several times to get it to work. As soon as it powers up. start hitting Break over and over.