Sorry, I was still trying to get it to work when I posted this thread. Still not working. Let me start by saying, I am very familiar with Yuneec drones. I have a Q500, H Plus, and H520 with multiple cameras. I use the H Plus and H520 for my business and have many hours with each. The issue with the H520 just happened out of nowhere yesterday. I plug it in after every couple flights to download the flight files into QGroundControl, and then upload them into Drone Logbook. The computer I am using is a brand new Lenovo Legion laptop, that I have used several times already for downloading files via USB. The firmware on the drone, transmitter, and all cameras are up to date. The computer is Windows 10, and just got a security update a couple days ago, and has all current drivers.
Yesterday, I flew 2 batteries in my backyard. I only wanted to bring the batteries down to storage voltage, because I don't like letting them sit. There's a tropical storm bringing rain to us for the next week, which started last night. Nothing went weird with either flight. I hand caught it, left the battery in the drone with 40% remaining, put everything back in the case, and brought it inside. I then took just the H520 out of the case, plugged the USB cord into the aircraft, turned on my laptop, opened QGroundControl, and then plugged the USB cord into the laptop, and I heard the computer recognize that a USB was plugged in with a tone. Immediately I knew something was wrong though. The power button lit up on the drone, the camera made its initiation tone and the gimble rotated to it's home position. But, the drone itself never made the startup tone, and none of the LED lights lit up on the arms. In QGroundControl, I refreshed the list several times, but it keeps saying to hook up the drone. I tried to hold the H520 power button to shut it down, but it will not turn off. I had to pull the battery out. I even tried a different USB cable, with the same results, and even tried different USB ports.
I have tried with the camera off the aircraft, camera on the aircraft, and with a micro SD card in and out of the camera. I have tried turning on the ST16S, and it doesn't recognize the drone or camera. I have tried to manually bind, with no luck. The LED lights on the arms aren't coming on at all, so I don't know if it's going into bind mode. When I plug it in to the computer, I hear the tone recognizing a USB device, but nothing shows up in my start bar, no button to eject the USB device, and it's not showing up in my file explorer.
Last night, I took the legs off and opened up the shell to check all of the connections. Everything is plugged in tight, no corrosion anywhere, the GPS light is blinking, and 5 (if I remember correctly) lights are blinking on the board.