Help my inspire out...

This seems to be similar to what happened to me when I took over the office Inspire 1 that hadn't been flown in years. It had apparently gotten a bit dinged up, and so the X5 camera was in a service centre somewhere and had never been picked up. We had an X3 with an Osmo handle, and so I had a really fun time trying to figure out why the X3 wouldn't connect to the Inspire 1 Pro - spent a few days fiddling around with firmware and messaging DJI.
And on top of it, one of the two controllers had a busted HDMI board, but once I swapped it over from an old P3 remote it happily connected. That seems to be what's happening with the OP here.
I bought the same unit that Davew listed above, and all has been fine since.