@LOM, Barryware: Help with bricked E4200

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xebbmw
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Joined: 19 Jan 2008
Posts: 17

PostPosted: Fri Apr 11, 2014 17:00    Post subject: @LOM, Barryware: Help with bricked E4200 Reply with quote
Hi,

I need your help to unbrick an E4200 v1. I acquired the router as a bricked unit, I have no history what exactly happened. Only the Cisco light was on when the router was powered, no lights on ethernet ports.

I was able to communicate with the router via jtag using wiggler cable and I tried to erase nvram and kernel. It did not work. Then I read the CFE and realized it was all garbage, did not look at all as a normal CFE from E4200 v1 from CFE collection site. So I got a good CFE, changed MAC, SN and PIN and wrote it back using jtag. After writing it, I read it back and compare the two files, but it was wrong again.

I took another approach. I used a flash programmer and read the flash chip (whole file). Then I inserted CFE using a hexeditor. Flash it back to the flash chip and as a result I have a network connection with the router, ping responds with TTL=100. So missing firmware that I tried to upload with tftp, but I was not able to send commands via serial connection.

Then I inserted a standard firmware (from Cisco, but I removed some bytes from header to have a really trx firmware). As a result the router was powering fine, network connection was available but the serial communication was stopping some moments after powering the router.

After more reading I reach the conclusion this might be caused by bad caps. I replaced the caps (CapXon brand) on router and the power adapter. The latest bootlog that I got is more complete, but still the router hangs after some time. I did not try pinging the router but browser access is not available.

It is also something strange with the router. When I power it for the first time I got network connection and the main Cisco light is flashing and also serial connection is working. After some time the light goes completely off. Router is not available by network. If I remove the power then wait a few moments and plug it again, I got a steady on Cisco light (no flashing), no serial connection anymore and no network connection either.

I attached the latest bootlog here, the most complete one.

Thanks a lot for your ideas.



bootlog3.txt
 Description:
Latest bootlog

Download
 Filename:  bootlog3.txt
 Filesize:  18.22 KB
 Downloaded:  479 Time(s)



Last edited by xebbmw on Mon Apr 14, 2014 14:23; edited 1 time in total
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Malachi
DD-WRT Guru


Joined: 17 Jul 2012
Posts: 7244
Location: Columbus, Ohio

PostPosted: Fri Apr 11, 2014 17:35    Post subject: Reply with quote
I tried to jtag my bricked e4200. I've tried tjtag, brjtag and zjtag. It always hangs. Which jtag are you using and what flash chip di you select when writing the cfe to it?

None if the recognize the flash chip. So using brjtag I selected a 16MB serial chip but it still hangs at erasing or flashing anything.

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xebbmw
DD-WRT Novice


Joined: 19 Jan 2008
Posts: 17

PostPosted: Fri Apr 11, 2014 17:42    Post subject: Reply with quote
I used tjtag 3.02 final. My chip is MX25L12845 and it was recognized by default by tjtag.

What is your flash chip model?
Malachi
DD-WRT Guru


Joined: 17 Jul 2012
Posts: 7244
Location: Columbus, Ohio

PostPosted: Fri Apr 11, 2014 17:48    Post subject: Reply with quote
Mine is a Winbond 25Q128BVFG.
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