I ran into the same issue described by bkloppenborg here:
https://forum.openwrt.org/viewtopic.php?id=23941

I upgraded the firmware and then waited for the router to restart.  No luck and now I'm seeing the same exact symptoms:
- Power Light Blinking
- USB Light On (Solid)
- DMZ light never turns on
- Won't reply to pings over WAN or LAN ports

From the post linked above, I should be able to recover the router using a serial console cable. 

Can I use the existing external USB port to console in somehow?  Or do I have to open up the router and add a stereo jack and then use a USB TTL cable that plugs into that jack and then plugs into my PC?

Thanks for any help setting me on the right path

OpenWrt / WRTSL54GS #39

(Last edited by fyi on 25 Sep 2010, 20:22)

Connect a switching hub between pc and router. Power off the router. Run the batch. Ex.

c:\> fw_upg 192.168.1.1 firmware.bin

Power on the router.

Before proceeding, download fping.exe for Windows from http://www.kwakkelflap.com/fping.html
Set your system IP to 192.168.1.100/255.255.255.0

Windows batch file fw_upg.bat:

@echo off
if not %1. == . goto next
echo Syntax: %0 [ip_address] [firmware]
rem echo Syntax: %0 [ip_address]
goto end
echo on
:next
fping %1 -l -T -n 1 -w 200
@if errorlevel 1 goto next
tftp -i %1 PUT %2
rem putty -telnet -P 9000 %1
:end

(Last edited by fyi on 26 Sep 2010, 08:13)

No, you can't.

Before doing firmware upgrage. I'd recommend connecting a hub and run Wireshark or Packetyzer to sniff the possible FailSafe UDP packet. Wait 2-3 minutes. If nothing received, then proceed with fping. Power off the router, then run:

fping 192.168.1.1 -l -c -s 1 -t 200 -w 50

Power on the router and check if there's any successful response. The response might come from CFE or OpenWrt FailSafe mode. If it happens right after router powering on, then it definitely comes from CFE which means tftp might work.

OpenWrt / A simple examination of ping reply upon boot

Thanks for the detailed response!  I'll get a hub and try it out.

Without hub and you're running Windows 2000/XP/2003, then you'll have to disable Windows TCP/IP Media Sensing in order to upload firmware to CFE. FailSafe mode is not related to this feature.

I heartily recommend that method, shown in the wiki here:  http://wiki.openwrt.org/toh/linksys/wrt … 4gs#serial

Of course, I'm biased, since that's a photo of my router there.    I'm dealing with some config issues with Backfire at the moment, and having that console running has been extremely helpful in ensuring a back door into the router no matter what I happen to screw up.  Even if you don't end up needing this now, I'd definitely recommend it for later down the road.

Lots of other good suggestions going on here, I'm sure that your box is still reachable, just work through the suggestions and hopefully you'll bring it back to life.

Can you verify what MLu did in OpenWrt / WRTSL54GS #39

If it's true, it will be a good news for other WRTSL54GS owners.

I can't, mostly because I don't run Windows.  LOL  But it's definitely possible that this worked, it really comes down to what state the router is in.  The first thing I did with both of my WRTSL54GS routers was to add the serial port, so I've always had that as a fallback and could always access the CFE bootloader to do the TFTP firmware loading.

No luck with the fping I will look into adding a serial port.  Thanks!

Just found something interesting so I thought I should write it here. Check the OpenWrt package download site and look for file prefix "kmod-usb-serial."

The above should be the drivers of well known USB to serial controllers. With proper setup, I think it's possible to access the console through the external USB port of the router.

OpenWrt / Serial port
OpenWrt / Fonera 2100 serial console need urgent help