Why can I control the gimbal but not the quad?
I can't arm, calibrate, change flight modes, or basically anything having to do with the actual quad platform. The RC link is good, GPS is good, camera feed and gimbal control are fine.
I got sporadic "weak signal" notices even when the controller is on the bench next to the quad.
This started after a crash, I had to replace the yaw arm and ribbon cable and it worked for a few flights but had a lot of brownouts (lost signal briefly and regained it). Then it started not arming occasionally. Now it won't arm at all.
Seems like a loose connection, but everything looks tight. The fact that it only affects signal to the flight controller and not signal to the camera or gimbal motors seems like an important clue.