I was wondering how to remove this access panel to get to the coaxial cable connection inside.

Hello there etzabo. Good day and thank you for reaching out. Just a reminder that DJI do not recommend for you to dismantle or modified your DJI drone. If you are having issue with your DJI drone it would be best to contact our DJI support team at https://www.dji.com/support . We will do there best to help and assist you. Thank you.

DJI Stephen Posted at 5-5 19:45
Hello there etzabo. Good day and thank you for reaching out. Just a reminder that DJI do not recommend for you to dismantle or modified your DJI drone. If you are having issue with your DJI drone it would be best to contact our DJI support team at https://www.dji.com/support . We will do there best to help and assist you. Thank you.

I understand, but I can pay far less money by simply replacing the $30 USD Coaxial Cable.