Hi. I have just got phantom 3 pro and am having huge problems upgrading firmware. I have tried everything I can think of and everything they seem to suggest on DJI website. When I plug micro sd into back of controller using sub adaptor all I get when I switch controller on is a light blue light that glows constantly. No beeping or anything even if left for 10 minutes plus. When I try to do the upgrade through the DJI go app it all downloads fine but when I go to upgrade it beeps for a few seconds with solid blue light then turns red and says upgrade failed. I noticed it also says old software unknown is this what's potentially causing me problems? I now can't connect phantom and controller. Any help great fully received. Many thanks Ben