The traces and the voltage drop points to a high resistance on the battery contact plugs. This is very dangerous. Overheating of the contacts will increase the resistance and this will increase temperature - and so on until bad things happen.
To illustrate the problem: Lets assume the resitance of the contacts will increase to 20mOhm due to oxidation. The drone needs 16A current hovering and more when goes fast. Lets take 20A:
Voltage on contacs is R*I 0.02*20A=0,4V --> Power on contacts: 0.4V*20A=8W.
8Watt makes a lot of heat directly on the defect contact!
Sometimes a good contact cleaner will help, sometimes the contact spring is done. In this case only replacement of the contacts will help.
But what has it to do with the camera?
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