I recently installed a new(used) gimbal/camera assembly and now I am getting a gimbal disconnected error. Does anyone know how to resolve this issue?

Hello there Stymie. I am sorry to read and to know that you are having this issue with the gimbal of your DJI drone and thank you for reaching out. Since you are having this issue, I would recommend you to contact our DJI support team at https://www.dji.com/support?site=brandsite&from=nav for further assistance. We will do there best to help you and give out the best resolution for this issue. Just a friendly reminder that  DJI do not recommend doing a DIY in fixing the said DJI drone to avoid further damaging the said unit. Thank you.