You are getting somewhere then ....
What IP did you set for your PC (tftp server) and the control board? These are supposed to be the same and as far as I can recall, you can NOT be connected to the wider network (at least from what I recall, but I could be wrong on that).
Them ALLLLLLL!
I get no response from 1.250 which the ping said was alive.
TFTP2.exe responds to 1.100 and 1.1, when I input to the S3 TFTPboot.
But it's looking for an img file
Know how to turn a .bin into a .img?
Edit: .1.100 was it's pre brick IP address