A new version of the popular OpenWRT firmware for various WiFi devices has been released recently. This is why I thought of upgrading my TP-Link TL-WR740N router to the latest OpenWRT version (Chaos Calmer 15.05-rc2). But unfortunately doing so actually bricked my router. When a WiFi router is bricked, the only possible way to unbrick is to use a serial cable and solder it to some points on the router’s circuit board. But lucky for me, there is also a very easy method to unbrick the TL-WR740N router.
Here is how you can unbrick your TL-WR740N router in a few seconds without needing any serial or JTAG cable:
- Power off the WiFi router.
- Download the latest firmware for the router from the https://www.tp-link.com/us/download-center.html.
- Extract the firmware BIN file from the download ZIP archive. Rename the BIN file to wr740v4_tp_recovery.bin.
- Download TFTPD64 server from http://tftpd32.jounin.net/tftpd32_download.html. You can use the portable version of TFTP server or install it on your PC – either way it works the same. It will ask for Firewall permissions which you should grant for it to work.
- Connect the WiFi router to your PC through an Ethernet cable.
- Open network settings in the Windows control panel. For this, you can press hotkey Win+R to open the Run dialog, type control ncpa.cpl in the Run dialog and press Enter. It will open Control Panel showing all of the configured network connections. Then right-click on the network connection icon for the wired connection to your WiFi router, and select Properties from the menu.
- Change the network adapter settings (the network adapter that is wired to your WiFi router) and set the static IP address to 192.168.0.66, subnet mask to 255.255.255.0 and default gateway to 192.168.0.1. Save the settings by clicking on OK button.
- Launch TFTP server and change the current directory to where the wr740v4_tp_recovery.bin is copied in step 3 above. Change the server interface to 192.168.0.66.
- First press the reset button (using a paper-clip or pin) of the router and then power it on. Do not release the reset button for 4-5 seconds after powering it on. As soon as you release the reset button, TFTP server shall flash the firmware and start the router.
- That’s it. Now you have a fully unbricked working WiFi router without actually needing any serial cables.
This method works for many models of the TP-Link WiFi routers. You have to rename the firmware file for your router according to your router model and version (in step 3 above). The original credit of this hidden unbricking method goes to bkil (http://bkil.blogspot.com/2014/12/hidden-tftp-of-tp-link-routers.html).