Crash the drone, gimbal no longer works, flash yellow. HDMI still functional. Crash was hard enough to dislodge 2 boots. Checked connections, all seem good. Is it toast?
I would guess you've got a motor that has become jammed or misaligned at the very minimum.
The motor control/stabilization and the video output are essentially isolated on the gimbal. So the video can still work and the motors or their control can be completely shot .