Hi! I read a lot of topic about this but nothing helped me. So i upgrade the firmware with no problems. In the end of the upgrading the app said restart my aircraft and controller. After that yellow led flashing in the drone and in the app shows "rc signal lost". I try to re link a lot of times, i format the sd card but nothing. I try to reupgrade the firmware but it always stop at 20% and 49% than it say upgrading fail. I am sad because i got the drone few days ago and a factory upgrade destroy it.