Agreed, do the firmware and get that issue resolved.There’s the possibility the camera has failed but I would have expected an error message to appear.
It could be one of FPGA chips that are programmed as part of the firmware updates. I would definitely try getting hold of a laptop or contacting someone who has one and use the Assistant 2 for Mavic program to update or reflash the firmware.
The thing is, it worked once, then it didn’t. That sounds like hardware. If not the lens, maybe the gimbal video cable.