I would think the battery swelled up and got dislodged. they are getting old. put a velcro strap around the Drone and battery to help keep it from popping out.
That will buff right out! ;)
DO NOT TOUCH A SCREW! send it to DJI and have it fixed. If for some crazy reason you decide to turn a screw DJI will know and your warranty will be voided. There are no parts you can get for it if you break something.