Two months ago (I've been away), I got my Inspire 1 and Zenmuse 5 gimbal/camera back from DJI's repair facility in California.

Since then, I have not been able to operate the drone.

The software issues a message that says "Gimbal Not Connected". It is connected, but, unlike prior occasions when everything was working, the gimbal does not do its little spinning dance when I boot the drone up, and I'm not seeing any view through the app.

Does anybody have any idea what is going on? I'd rather not send the unit/camera/gimbal back for "repair" since it hasn't even been functioning since the last repair.

The repair I had done was on the gimbal because the band through which the data is passed tore off in a crash and one of the gimbal's brackets broke also.

I would be checking the socket that the camera assembly seats in to make sure all the little connections in there are clean and in good order and if that is ok remove the gimbal mount and check the two ribbon cables on the back side are plugged in properly.

As  Phantom Paul says , check that mesh between the Camera Gimbal and the Vibration board, also follow the 2 flat ribbon cables from the Vibration board to the AC, sometimes they can get "crimped " or pull out of the socket and cause problem , examine this closely , push the vibration board down so you can see the flat ribbon cable  between the aircraft and the Vibration board . , I have heard of this before, more than likely this is where  your problem lies .  Make sure also that you line up the back slot guide  of the X5 BEFORE getting the round gimbal into the vibration board , once the back of the camera is in the slot the camera should just ease up and then you can lock it in place .  
During the crash I bet the flat ribbon cables were pulled out  or broke as well. Sometimes there is more damage than we just see , this is a simple fix and you can order new flat ribbon calbes as well.  

good luck , let us know what you find

donnie