If the Centre frame is not damaged then the most common cause is the RC firmware is newer than the aircraft firmware and the versions are incompatible. There’s a lot of threads on this.
You can try to downgrade your RC firmware and see if that works.
Or what I have found works best is to find someone with a RC with old firmware, link to that RC and get the aircraft out of travel mode, turn off the old RC, relink my RC, turn off the RC, attach camera then upgrade aircraft firmware.
I keep a RC on old firmware just for this. But I am in Australia so don’t think I can help.
What may work which I haven’t tried is to manually get the aircraft out of travel mode by turning the screw from underneath with a screwdriver, turn on the AC, attach the camera and upgrade the firmware. May be worth a try? Remember to leave your RC off while upgrading.