Holybro X650 Neopixel firmware (Pixhawk 6C)

Hello everyone

I have a Holybro X650 with a Pixhawk 6C and I am trying to get the Neopixels working. Please note I am not an experienced drone user.

I followed the instructions here:

Managed to install the beta firmware eventually, but after that the drone will not connect to QGroundControl. If I install the latest stable version of PX4 back onto the Pixhawk then it connects just fine.

I am only using USB connection currently. No battery.

I can see it appearing in device manager and being assigned a COM Port.

Is the beta firmware not compatible with Pixhawk 6C?

Many thanks
Dan