My APM 2.5+ won't connect on the 3DR radios or USB. For the past few days, I've noticed the HUD starting to twitch (+/-3 degrees) when the plane is sitting still. Today at the field, I had trouble getting a GPS lock (which has never happened- I have a uBlox). When I recycled power, APM stopped outputting MAVlink packets and wouldn't connect on USB (or show up in the device manager). The LED behavior is correct.
I wonder if maybe it's a power issue. However, I use the 3DR power management board, the jumper is pulled, and I power servos with the ESC/BEC.
I have also been testing some electronics on the plane, completely separate from APM but next to it. It was a network megapixel camera, a beagle bone, and a mini network switch. Is there any chance that electromagnetic interference may have caused my board to malfunction? I used Tetracam next to APM a while back and had definite GPS interference problems.
Oh, and any chance it could be electro-static discharge?