Motors won’t spin Hollybro 6C Pixhawk

I built a F450 frame years ago and put a Hollybro 6C Pixhawk to replace my old unsupported controller. I downloaded firmware and programmed through Mission Planer. I cannot get the motors to spin in the Mission Planner or not. All I get is a beep…beep etc. can someone help me?

For MissionPlanner and ArduPilot, use discuss.ardupilot.org.