06-12-2019 10:50 PM - edited 06-12-2019 10:52 PM
You'll need to contact the GoPro Support Team
The doors can be tricky. If the safety button doesn't pop back up or if there is any debries on the gasket (even a small fine hair) then the waterproofing can be compromised. My son has the HERO7 White and uses it in the ocean often. The camera is waterproof, but needs to be sealed correctly and clean properly after use in water.
Although water damage is not covered under warranty, you should contact the Support Team so they can give you some options. If you feel that the doors are defective, an easy verification can be done. Make a video using a different camera/phone of the GoPro showing the doors open. Take the battery and your SD card out of the camera. Place a thin piece of tissue in the battery compartment and place a small piece (must be smaller than the diameter of the gasket and very thin) under the media door gasket. Close the doors completely, making sure the safety button pops up, and then submerge the camera. Dry the exterior completely and then open the doors. If they are defective the tissue should now be wet and you will have video to show this to GoPro.