How to reinstall original firmware Linksys WRT3200ACM

Hi, I have the same router as you and I've reverted back to stock firmware plenty of times.
You'd have to SSH into your router, unfortunately, but I find this the easiest way.

  1. I use CMD for this: ssh root@192.168.1.1 then use your password.
  2. cd /tmp
  3. wget http://downloads.linksys.com/downloads/firmware/FW_WRT3200ACM_1.0.6.186168_prod.img
    I use the sysupgrade command to actually revert back. For some reason, this is the only command that works for me.
  4. sysupgrade -F cd/tmp/(name of the firmware).img

The -F forces the update.