TP-Link doesn't differentiate between v1 and v1.3 on their website, and there doesn't seem to be any practical differences between v1 and v1.3 documented anywhere. I can't be sure, but I think the procedure should work equally well for all v1 devices. I didn't notice until now you also have a v1.3, same as mine.
A very detailed description, it assumes you use Windows:
- Download tplink_wdr4900_v1_130424_noboot.bin as I linked to
- Download Tftpd32 zip file, the latest version is 4.50, and the file you should download is named tftpd32.450.zip
- Unzip the Tftpd32 zip file you just downloaded to somewhere
- Put the firmware image you downloaded at first in the same folder as tftpd32.exe, and rename it to "wdr4900v1_tp_recovery.bin"
- Set the IP address of the Ethernet interface you will use to 192.168.0.66, subnet mask 255.255.255.0. Guide for setting static IP address if you need it. You can leave the default gateway and DNS servers blank (ignore the warnings, you won't have internet access while you do this anyway), as long as you set the IP addresses to said values.
- Connect your router to your computer, but don't power it up yet.
- Run tftpd32.exe from wherever you have put it.
- Press "Show Dir" button, you should see the wdr4900v1_tp_recovery.bin file listed there. If you don't see it, you can press Browse to change to the directory where you have put it, or copy it to the Tftpd32 folder. Do what it takes to get wdr4900v1_tp_recovery.bin in the "Show Dir" list.
- Choose 192.168.0.66 from the Server interfaces dropdown menu in Tftpd32.
- Hold the reset button on your router, then power it up. Do not release the reset button at any point.
- Tftpd32 should report a transfer, it will show a progress bar. It is fairly quick, when the progress bar disappears the transfer is finished. Just to be safe, keep holding the reset button about 3 seconds after the progress bar on your computer disappears, then let go of the reset button. The router should still be powered on.
The router will now flash the firmware image and reboot. In my case it didn't reboot properly, I just left it for five minutes after letting go of the reset button, and then powered it off and on. Change your IP address configuration on your computer back to automatic, or whatever you had it set to. The stock firmware has IP address 192.168.0.1 by default.