Removed router board and hooked up a serial 3.3v ttl connection. This allows you to see what is going on and why the update is failing.
The firmware uploads correctly, but the router then checks for hardware ID, which for the erased firmware is now ff ff ff ff etc, it wants to see 29763551+04+32.. no go
Board HW ID mismatch, it is forbidden to be written to flash!!
With serial 3,3v ttl interface cntl c twice, this gets you into a command line mode, type ? to see the list of commands.... there are a lot of commands.
"board_hw_id_set" good set HW ID
" board_model_id_set" need this one too
Bingo.. now the firmware will upload and run. Router good to go..
WOW! things are a little different than I expected...
Did a serial probe of a stock out of the box unmodified wrn2000v3 firmware V18.104.22.168 router and
board_hw_id is set to ff ff ff ff
board_model_name is set to ff ff ff ff
There is a command "protect [Enable Disable]" that enables or disables FLASH write protection.
OK bulldog, I will test if I can upgrade an unmodified router with tftp..... try uplaoding a netgear firmware update.
No the update fails with "HW ID on Board mismatch, it is forbidden to be written to flash!"
Looks like its not possible to tftp any firmware to the router without without board_hw_id set and board_model_name set or protect disabled. Serial command line can do that, I am not sure about OpenWrt.
I guess one could have a GUI firmware update that wrote to the 9f3f000 area that would allow tftp updates.
So far to me it looks like serial is required to set up the router to accept and run tftp uploads.