How do i fix the flashing green light on AirPod case?

If there's an Airpod inside try removing it and replacing it. It could be a poor connection. If that doesn't work then try resetting:

Click on this link to learn how to 'Reset your AirPods --> https://support.apple.com/HT209463

Click on this link to learn 'How to reset your AirPods Max '--> https://support.apple.com/HT211904

If that doesn't work them have them evaluated by Apple.

AirPods Service and RepairLearn more about AirPods service options, warranty, and pricing. Click here --> https://support.apple.com/airpods/repair/service