3.29 Firmware BC296d

[lockoutspecialist]

Been trying off & on for the past 2 months to download 3.29 into bc296d, It tells me imposable to rewrite to scanner on the computer display. Has anyone had this problem? If so how did you fix it if you did? I have 3.21 now radio works fine I wonder if I need it?
I reseted the radio then downloaded firmware, got comm port error re download firmware try again. tried but did not work.