I paid the $75 for the 25 year license and downloaded the endpoint manager that is part of Freepbx. It says ver 13.0.15.
Do you have other phones connected to the pbx? If not, have you confirmed that you can ftp to the pbx and log in using the same login that you have entered in sysadmin?
I have found with the 7960s that turning off the dhcp and entering a static address & subnet is better. Also enter 255.255.255.255 under network for option 1 and be sure to enter the pbx address for the tftp server. Also check the permissions in your \tftpboot folder.