S3300 Bricked Firmware Recovery Howto


S3300 Bricked Firmware Recovery Howto

Good day all,


I just spent the better part of 8 hours recovering a bricked S3300 switch (GS728TXP) where the web-interfaced crashed mid-firmware-update. Backup firmware was also broken.


Couldn't get official support because the unit was a 2nd-hand import and our single local  Netgear distributor in South Africa refuse to touch anything they didn't sell. We also couldn't replace the unit as they had no stock of a similar unit for over 6 months now.


Just posting this here, maybe someone can save themselves some money and time as it doesn't look like we will get official support for this sort of problem. I will summarise it here, if you need more direct instructions or assistance, just ask.


This is what I did:


1. You need a TTL RS232 UART adapter/cable/interface. I used a Raspberry Pi unit available from RS Components (TTL-232R-Rpi | FTDI Chip 1m USB to UART Cable in Black | RS (


2. At the back of the switch there is a port labelled "Debug". Complete undocumented with 4 pins. Connect the TTL RS232 UART interface with the following pins: 1: empty. 2: TX/Output. 3: RX/Input. 4. GND/Ground.


3. Open up a serial console on the interface (I used putty) with the settings printed next to the DEBUG port. 115200-N-8-1.


4. With my situation, image-1 failed to boot because of a checksum error (corrupted image) and image-2 just continously rebooted the unit for no reason at all.


5. Pull the power, hold in the factory defaults button and keep holding it in until you get a prompt BCM.0>


6. Run 'sh' for a workable shell, and then 'su -' to elevate permissions. Once you are there, you need to run /etc/profile (/bin/sh /etc/profile) and "mount -a" to have block devices assigned and tmpfs on /media to download the iamge.


7. Put the firmware image somewhere on a TFTP server on your network reachable locally.


8. Navigate to /mnt/media (cd /mnt/media) and use tftp to download the image (tftp -g -r s3300v6.6.4.28.stk


9. Write this image into the block device for the active image (cat s3300v6.6.4.28.stk > /dev/mtdblock4). If you're using firmware-slot-2 this will be /dev/mtdblock5. You can double check by catting /proc/mtd


10. Reboot, it will finish the firmware configuration work and you'll be sorted out.


Hope someone else finds this useful.

Message 1 of 2
NETGEAR Employee Retired

Re: S3300 Bricked Firmware Recovery Howto



Welcome to the community! 🙂


Thank you for sharing the steps you did on how to recover the S3300 switch.  This is very helpful to all S3300 users here in the community.






NETGEAR Community Team

Message 2 of 2
Top Contributors
Discussion stats
  • 1 reply
  • 2 kudos
  • 2 in conversation