How to unbrick a netgear wnr-3500l v2 without serial ttl cable

Yesterday i flashed my wnr3500l v2's firmware but something went wrong. Al i got was an amber led. The router was bricked. When i pinged the device i got host unreachable but when i pressed the reset button for 30 seconds i got maybe 4 replies but after that destination unreachable. I tried to flash the firmware back to the device with a tftp client without results

I don have a serial TTL cable but i managed to unbrick it without it.

After some searching over the internet i found out that a wnr3500l is possible to unbrick  it without serial TTL cable see this post: http://blog.zipleen.com/search?q=how-to-debrick-netgear-wnr3500l. It worked for me.

The PCB layout is different of the two routers. They also have different NAND flash chips. https://deviwiki.com/wiki/Netgear_WNR3500Lv2

1. Download the firmware .chk file of your choice.
2. Download a tftp client. I used the standard tftp from the Linux repository.
   

   apt get install tftp

   but a windows client will also work

3. Now the router should have a working firmware, you can reset to defaults, fSetup your network interface computer to 192.168.1.2 / 255.255.255.0
4. Open the router. 
• Remove the bottom screw
• Drag the plastic cover down of the backside of the pcb (when you face the front of the router it is the left cover)(it will kind of slide), maybe with the help of a screwdriver to release one of the sides
5. Turn on the router a wait for all the lights to flash and when they turn off you have to short & hold  pins 44 & 43 (both i/o pins) of U4, (it is a 48 pins TSOP type I ic see datasheet page 11 for pin count)  and press the reset button. The power led should starts flashing green. When you ping the device now you should get a reply.

6. Now you need to open the tftp client to upload the *.chk file.
   type the following commands.

• cd Downloads (or whatever the file you downloaded is)
• tftp 192.168.1.1
• binary
• put WNR3500L.chk (this is the filename that you downloaded, you can rename it to whatever you want)
• Hit ENTER  in the tftp client. Your power led should be flashing green and the network port should have activity briefly. The tftp client should send the file. after that the router will take 2-3 minutes to flash the file. The power led flashes orange and green. 
7. Now the router should have a working firmware, you can reset to defaults, flash another firmware and do whatever you want again.

 

link to datasheet nand flash: https://www.digchip.com/datasheets/parts/datasheet/2/5675/S34ML01G100TFI000-pdf.php