Might Have Bricked 4331 ISR

[ncombs1407621308]

So I was setting up a fresh Cisco 4331 ISR and changed the line vty 0 15 to have priv 15 and forgot to actually setup a username/password before unplugging the console cable. So fast forward about an hr's time after I got done configuring the switch I attached to it, and all I see is "Router>". I tried doing "en" to enable it, but with no luck with the device saying "No password set". In this state I did what every net admin does and googled how to password reset Cisco 4331 ISR and it stated to do a break sequence on boot. Here's where the fun begin. I'm using putty and tried all break sequences listed on Cisco's website https://www.cisco.com/c/en/us/support/docs/routers/10000-series-routers/12818-61.html and while I'm sure they work, while I'm consoled in I see no boot sequence it just eventually ends up on "Press RETURN to get started!" after a long black screen. I tried ctrl + c, ctrl + ], ctrl + ] - send brk, physically pressing break key and using putty special break command, ect. At this point I'm at a loss as I cannot get into rommon to reset the password/give it a new one any help is appreciated.

[balaji.bandi]

Ok do this step :

Power down complete router

connect the console cable ( capture the logs here from boot process)  - config putty terminal config - Configure the terminal to operate at 9600 baud, 8 data bits, no parity, and 1 stop bit (9600 8N1).

Turn on the device. (wait 30 seconds before powering it on again after power off)

you will see a message that you need to do ctrl +c to interrupt.  ( some time break keys works)

https://www.cisco.com/c/en/us/td/docs/routers/access/4400/troubleshooting/guide/isr4400trbl/isr4400trbl02.html

[ncombs1407621308]

Hmm so I hit the power switch on the back of the 4331 and unplugged the power cable for a minute, plugged it back in and flipped the on switch, lastly spammed ctrl + c every 2ish seconds, and same result. The router will black screen through putty until it just says "Press RETURN to get started!". Would pulling the cmos battery do anything and letting the motherboard charge clear?

[Leo Laohoo]

What type of console cable is used?  Is this the one with an RJ-45 at the end?

If this is the case, are you using a USB-to-Serial coverter?

[ncombs1407621308]

correct it is a USB-to-Serial with the RJ-45 connector/attachment

[Leo Laohoo · Accepted solution]

There is a large number of "compatible" USB-to-Serial converters that are not using the correct chip.  One of the "features" is the inability to use the Ctrl+Break.  

If I remembered correctly, one can use a USB A to min-USB cable and connect directly to the back of the router and it will work just fine.

[ncombs1407621308]

Thanks I'll have to find and purchase one online in order to try, but ill defiantly give this a go.

[Leo Laohoo]

Have a look at some accessories for cameras -- The early generations usually have USB A to mini-USB.  

[ncombs1407621308]

This did it thank you!

[Leo Laohoo]

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@ncombs1407621308 wrote:

This did it thank you!

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Good to hear it is working. 

Permit me to provide additional tips: 

1.  One cable is not enough.  Get, at least, two:  One in your drawer and another in your "grab" kit. 

2.  Dark coloured cable is a bad choice when fumbling in darkly lit location.  

3.  2 metre cable can go a long way.  Measure the height from the top of the rack to the floor, and then some.  If one was to be sitting on the floor with a long console cable, what would the length be.  

4.  Experiment on which "brand" suits.  Not all brand are "good".  

Hope this helps.

[Georg Pauwen]

Hello,

it might just be easier to do a hard reset to factory defaults:

https://dcloud-cms.cisco.com/help/reset-router

[ncombs1407621308]

I thought this as well, but sadly I cant seem to find a reset button for the Cisco 4331 ISR. I also can't enter enable mode because no username/password which is where Im stuck.

[ncombs1407621308]

Here's the continual logging. Like I stated it doesn't show anything when booting up it just goes straight to return.

=~=~=~=~=~=~=~=~=~=~=~= PuTTY log 2021.10.07 17:51:41 =~=~=~=~=~=~=~=~=~=~=~=

Router>
Router>

Press RETURN to get started!

Router>
Router>
Router>en
% No password set
Router>?
Exec commands:
access-profile Apply user-profile to interface
clear Reset functions
connect Open a terminal connection
crypto Encryption related commands.
disable Turn off privileged commands
disconnect Disconnect an existing network connection
do-exec Mode-independent "do-exec" prefix support
enable Turn on privileged commands
ethernet Ethernet parameters
exit Exit from the EXEC
help Description of the interactive help system
ip IP SLA Exec Command
lock Lock the terminal
login Log in as a particular user
logout Exit from the EXEC
mrinfo Request neighbor and version information from a multicast
router
mstat Show statistics after multiple multicast traceroutes
mtrace Trace reverse multicast path from destination to source
name-connection Name an existing network connection
pad Open a X.29 PAD connection
--More--   ping Send echo messages
ppp Start IETF Point-to-Point Protocol (PPP)
release Release a resource
renew Renew a resource
resume Resume an active network connection
rlogin Open an rlogin connection
routing-context Routing Context
set Set system parameter (not config)
show Show running system information
slip Start Serial-line IP (SLIP)
ssh Open a secure shell client connection
systat Display information about terminal lines
tclquit Quit Tool Command Language shell
telnet Open a telnet connection
terminal Set terminal line parameters
traceroute Trace route to destination
tunnel Open a tunnel connection
where List active connections
x3 Set X.3 parameters on PAD

Router>
Router>
Router>

Press RETURN to get started!

Router>
Router>
Router>

[SAMEHELSAMMAK]

use ( Cisco CLI Analyzer software ) from cisco

it will work with your cable or the usb cable when you get it

[ncombs1407621308]

Doing same thing as putty it just boots up.