I also remember other that when they complained to tech service about gimbal not recognize/intialize is the tech quickly rule out a battery problem.
Sometimes changing the gimbal to a new one fixes the problem. Others needed to change the karma core to fix it.
And if its karma core, 2 things are in my theory.
One would be the usb-c in the gimbal port infront of the drone and the second would be the battery connectors inside the drone that connects to the battery.
that could be worn out and not giving power to the gimbal.
If you watch youtube youll see most people slam that battery hard to make sure it is locked.
And the way the remove the battery is the pull it out hard.
These creats friction and will wear out those gold tabs.