Has anyone used the edison version with the external antenna? I have several modules with the chip antenna and for each of them, I have used a consistent and documented process for upgrading the firmware, changing the root password, configuring a static IP for the wifi etc., so I am pretty confident the process works. I recently purchased a module with the external antenna and have had nothing but trouble configuring it. For example, after 'flashing' the latest firmware, I still get the losing 1st character on the serial terminal issue and when I type "configure_edison --version" instead of the version, I get an error in that '--version' is not a valid argument. I can join a wifi network but the association does not stick across reboots. This seems to imply that the flash didn't work, but now what?
Is there any differences in the firmware I need to install for the external antenna version?
No, there shouldn't be any difference with your Edison's firmware. What are you using to enter your board's Linux terminal?
I'd suggest you to try to flash the latest Yocto image to your board using the Flash Tool Lite. You can find this tool and the latest image in Intel® Edison Board Download | Intel® Developer Zone and a guide on how to use it in Flash Tool Lite User Manual | Intel® Developer Zone.