Recently I traded my iPad mini 1 that is as old as my sister for a nonfunctioning 3dr solo drone on the Facebook marketplace. The guy that traded me it said he could never get the controller to communicate with the drone. He said broth devices turned on perfectly and that he only flew it for 45 minutes before it didn’t work again. I knew there had to be a way to fix this, so I spent several days researching, talking to the developer of Solex for android, and even joining a Facebook group. This group was kind of enough to walk me through the entire thing. They gave me this link (see at bottom of post) to the instructions when using the Solex app. If you have an iPhone, you’ll need to backtrack to the origin post and click on the link for it. Good luck! I hope this fixes your issue!