Why would this happen?

I have a 3DR Pixhawk that will not load FW. It almost gets there than just shuts off. It is a new one out the box. My other ones work good, any ideas? And when I plug it on USB the arm light will not come on, it will if I plug it into my battery.
Thank you for your time.

Disconnect everything from the pixhawk except the safety switch. Hold down the safety switch and plug the pixhawk into USB of your computer and try to program it again from Mission Planner.

Also make sure the SDCard is working ok (try it in your PC) and is seated properly in the pixhawk.

You might also need to try different computer USB ports or a different USB cable.

If its still bust contact 3DR.

Let us know how you go.

Thanks, Grant.