Zenmuse X5 - gimbal and camera irresponsive

I was taking a panorama when suddenly the Gimbal/Camera became irresponsive. Once grounded, I restarted the aircraft, checked the connections but nothing has changed.
The camera looks energised as the green led flashes a couple of times when I turn the AC on, but I can't take any photo. There is no video signal connection with the RC.
I tried a FW upgrade, but the process didn't start.
I don't know if the problem is with the Zenmuse or the AC.
Any clue?
I haven't made any firmware upgrade recently.

Already checked the connections and the cables between the AC and the connecting plate. I forgot to say that during the last panorama sessions the gimbal started yawing erratically. It wasn't able to frame in the right direction.