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[asbokid]

Do you have links for the software you used for re-flashing the device, and the firmware image(s) you tried to flash?  It's possible the problem might be evident from studying these.

Also perhaps you could cut-and-paste the commands you used to reflash, and the exact error responses.  The [code] tags for this forum are good for this.

It is unusual to totally brick a device to the extent that it needs physically hacking. Replacing the bootloader is a prime suspect when that happens.   It's almost never necessary to reflash the bootloader. But sometimes the firmware image is bundled with a bootloader as well as the kernel and file system image.  So the whole lot gets flashed in.

However, if that bundled bootloader is somehow incompatible with the hardware revision of the device (and it can only take a very minor change), it could still brick the device. At that point you do have to physically open it, attach a JTAG cable, and re-flash the original bootloader back into it.

As for which method to use - UART or JTAG .. I would try UART (serial) first, since its cheap and easy.  A UART cable is only a pound or two (search ebay for pl2303). But if the bootloader is toast, UART won't work any way.   JTAG cables are a bit more - £5 or £10 for a better USB-based adaptor, e.g. clones of the Altera USB-Blaster.

Cut and paste the exact commands you tried, and the exact reports. Maybe repeat exactly what you did before, and log everything to a file, and paste it here using the [code] tags.

Good luck!

cheers, a

[Justino]

OK, will log everything best I can over the weekend.

What software do i need for the jtag cable to work?

thanks

[les-70]

  Sometimes a long hard reset (long press ~30sec with paper clip) followed by a similar reset while powering up and connecting to an XP machine and just leaving it there in a limited connectivity state for an hour or so, will invoke connectivity and the web gui upload page appearing "spontaneously" with no login. This seems to be a DG834 safety mechanism for bricked devices.   I then had the web gui firmware update fail again but after this the windows update utility worked fine.  I would reflash with the Netgear firmware first and then DGteam with the windows update utility. With DGteam the 26o driver version often bricks routers the 23o version is safest.  Good luck if you decide to try it.

[Justino]

Les,

I will give it another go, but i have left it overnight on one occasion on the windows recovery utility, and the router didn't show up in the Device list.

Are you saying just leave it connected to an XP machine with or without the utility running?

[les-70]

  With nothing running.
    I think the windows update utility requires DHCP to be working or if not for connectivety to be present via set fixed IPs.  Since it not working for you I assume the bricked router is not providing DHCP.  Leave the ethernet adaptor expecting DHCP.  With the router powered up this will then show as limited connectively and a useless default windows IP address.  When (hopefully it will) connectivity eventually occurs just open a browser and it should go only to the update page.   I found this tip googling but can't find it again today after a short search.

[Justino]

Should the router be in idle mode (light flashing ready for up date) or just powered up? When I power mine up as normal I just get a red power light.

[les-70]

  Possibly, I am afraid that I can't exactly remember and I am not keen to use a DGteam 26o version to try it again!   It is just powered up with the reset being pressed.  It certainly does not work like it should. i.e. the windows update utility won't find it and there will be no ethernet connectivity.  Just the power up with reset on and try leaving it in what ever state it is. Red light on or otherwise.  I assume you won't have any GUI connectivity on 192.168.0.1 to begin with but with luck the update page  will appear after a long wait. 

[Justino]

Has been on since this morning with no success, so far.

I'd like to have a stab at jtag, but need some advice on what software to use then the process involved.

[asbokid]

UrJTAG is the tool I always use.  It supports loads of different cables.  Quite often though, the PCB has been trivially disabled in some way to prevent the use of JTAG.  e.g. by the omission of a solder link somewhere.  It can take a while to find it.

cheers, a

[Justino]

Managed to get a replacement DG834N for £10. Still want to try and fix this one though, but the question is do I dare try and upgrade the firmware again on the new one. If I do, should I use my Xp machine on sp2 running the net gear utility, or use Ubuntu on the same machine, and use nftp??

[Justino]

UrJTAG is the tool I always use.  It supports loads of different cables.  Quite often though, the PCB has been trivially disabled in some way to prevent the use of JTAG.  e.g. by the omission of a solder link somewhere.  It can take a while to find it.

cheers, a

Has the DG834n been disabled for jtag?

[Justino]

Found this

http://www.suntekstore.co.uk/product-14003019-usb_blaster_cable_cpld_fpga_jtag_programmer_altera.html

included is

1 x USB BLASTER Programmer
1 x 10-Pin JTAG Connection Cable
1 x USB cable

looks ok I think, would just need the jtag header for the circuit board which are easy enough to get off ebay.

So on the basis the above jtag programmer will work, I have downloaded urjtag, soldered on the header pins to the router circuit board, and connected to the programmer, what is the process for  loading up the firmware via jtag?

[les-70]

  I can't advise on unbricking via the JTAG but if you have not altogether lost heart with other approaches or get bored while things are delivered you could repeat the windows update procedure (on an XP machine) and also the "waiting for a GUI" procedure with the PC Ethernet adaptor set to a fixed IP in the router range e.g. 192.168.0.100. 

[asbokid]

Yeh, follow les-70's advice and check whether there is any ethernet activity from the device. e.g. set your PC NIC to 'promiscuous' mode, and monitor for ethernet traffic.  Also try port scanning the common ports on the IP blocks for the three private networks using nmap or similar.  It's possible that its default IP address is now something unexpected, hence the failure of tftp to connect with the device.  That's a common point of failure.  Flashing in new firmware and overwriting the old network config settings, etc.  So the device ends up on a different subnet.

What were you flashing into it when it failed?  A firmware image containing a bootloader?  Using JTAG, you will need a NAND image (or part-of) to flash back into it, rather than a pre-built firmware image.   Generally you would only use JTAG to re-flash the bootloader. Then you flash the rest of the firmware - the kernel and filesystem(s) - into the device using a daemon running on the network stack of the bootloader.

JTAG'ing is an absolute last resort.  It's also possible that the NAND IC has physically failed.  NAND failure becomes more likely as the flash ICs age. SFAIK, failure occurs during programming and erasure. Not during reading.  A bit refuses to set (1) during the high voltage erase process.    And the NAND f/s drivers of these devices are not very intelligent, and can't cope well with physical errors.   Most have no wear-levelling and will only work with a file system or bootloader that is stored in a continuous block of NAND pages.  So if one NAND page fails in the middle of a compressed file system - or worst case scenario a NAND page fails in the bootloader partition, then the device becomes a doorstop. Unless you are willing to replace the NAND flash IC.  Which isn't worth the time and expense for a five year old device that can be bought s/h for just £10.

Good luck whatever you choose to do

cheers, a

[renluop]

Probably irrelevant, but I have been testing my old DG824 v3 loaded with Team FWare.

Had devil's job setting up whilst using Chrome, but seemed IE was much friendlier.