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How to Unbrick a TPLink MR3420 Router?

How to Unbrick a TPLink MR3420 Router?

TP Link MR3420 Wireless Router
TP Link MR3420 Wireless Router

Yes, my bad luck on routers continues! However, let me share some good news on this post.

How did I brick my router?

We are using a TP Link MR3420 with a USB Dongle for our internet connection. One day I felt adventurous and I tried to flash a custom firmware (openwrt) to the router. The instructions were easy to follow from the openwrt wiki.

After a few minutes, the router was reborn with a new firmware however there was just one problem. My USB dongle doesn’t work anymore so in panic, I decided to re-flash the original firmware from the TP Link site.

V2 – https://www.tp-link.com/ph/support/download/tl-mr3420/v2/

The install failed! By flashing the original firmware over openwrt I managed to screw up the component that handles booting and I ended up with a router that does a boot loop. It would try to power on (power led on) then all led lights will blink; then it will repeat again to the power led on. If you press the WPS/Reset button; the last led light (WPS) will light up for a few seconds then it will go back to the original boot loop pattern.

How to unbrick the router?

I spent the next few hours trying to research on what would be the solution to solve this problem. One solution that was prevalent on the net requires opening up your router and connecting to it via serial cable. I don’t have the skills nor the equipment to do that so I thought I’m doomed to buy a new router.

However, as I read through the comments on different blog posts showing how to recover via serial cable, I happen to chance upon an alternative solution. This solution doesn’t require a serial connection.

How to Unbrick the MR3420 Router via TFTP?

This was the guide I followed in order to revive the router. The initial guide was to unbrick it via a serial connection but this is a different soultion.

http://blog.technicentral.com/index.php/2-routers/1-mr3420-unbrick

(Lifted and Modified from) Here is what you need:

  1. A LAN cable
  2. A machine running Windows XP or Windows 7 – I used Windows 10
  3. The modified firmware (https://www.box.com/s/kps8yu3wszywuhqzy0c3)
  4. A TFTP Server, for Windows users I recommend (tftpd32.jounin.net)

Now follow the following steps:

  1. Turn off the router.
  2. Download the firmware (https://www.box.com/s/kps8yu3wszywuhqzy0c3)
  3. Set you PC lan adapter to fixed IP 192.168.0.66
  4. Plug the lan cable in the PC and in the WAN slot of your router. I plugged it on the first lan port
  5. Rename the downloaded firmware:
    Original Name: MR3420v2_FactFirmware_NoBoot.bin
    New Name: mr3420v2_tp_recovery.bin (all lower case).
  6. Copy the file in the root directory of TFTPD
  7. Start the TFTPD server
  8. Press and hold the router’s reset button then power it on.
    While holding the reset button on your router power it on and VERY quickly start the TFTPD server. or, have TFTPD server running before you power on your router. 

If all goes well you should see information on the TFTPD server that the recovery file is being downloaded, after a short period you will notice the Led flashing differently on your router… job done.

Once I saw an activity in TFTPD, I got excited. Soon enough, the router had a different blinking pattern to it. I quickly checked 192.168.0.1 (router’s default address) and I managed to get in! My router is alive!

Let me know if this also worked for you or if you encounter problems.

Till next time,

Allen

3 replies on “How to Unbrick a TPLink MR3420 Router?”

Thank you bro, it help me debrick without serial connection, lots of people are dont know about these method still using serial connection.

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