Note: You must have access to the console port of the router for these steps.
1.)Connect to the console port.
2.)Power cycle the router.
3.)When the ARN starts cycling through diags, press Ctrl+C followed by Enter. Keep repeating while the router is booting and it should take you into diagnostics mode. If Ctrl+C does not interrupt the boot sequence, press the Pause/Break key after Ctrl+C<Enter>.
4.)At the diagnostics mode prompt, type diag_1>> and press Enter. This will put you at another prompt.
5.)At this new prompt, type in d/l/n:5 410000 0 (leaving spaces between the 5 – 4, and the 0 – 0). This will erase the Manager password from NVRAM.
6.)Type boot, then press enter, or simply power cycle the router.
7.)When the router boots, and you get the login prompt, it will not prompt for a password after you enter in “Manager”.
8.)Once you are logged in, type password manager <password> to change the Manager password to a new value.