A recent attempt to flash a new firmware to my Netgear WNR3500L resulted in the top power light staying orange. At first, it seemed to take a tftp attempt to 192.168.1.1 on boot up with the special boot up sequence however I could not get it to work.
After reading online, I purchased a USB-TTL adapter on eBay and waited for it to arrive. Following the unbricking guide, I could see the router boot up via the serial port (using the USB-TTL adapter). I was able to enter the CFE console (I found it easier to press and hold down CTRL-C and then power up the device as PuTTY kept sending the key sequence). However the Ethernet portion of the router never came online so while I could ask it to accept a tftp attempt by starting tftpd, it was of no use.
I almost gave up, however some searching found a report of the same problem
and the suggestion to try
nvram erase. I ran the command and after the prompt
came back, cycled the power to the device. On boot, I was again able to enter
the CFE console but this time the Ethernet portion of the router came up and
a quick tftp of the stock firmware and I was back online.