Revisiting the thread a bit later....never got the remote synced with the a/c. After replacing the main board with a new one supposedly for the 4K brings the question, did I really receive the correct board and/or processor? Saw many comments on line and from those selling the DJI parts that the board I bought should work on the 4K, Pro, etc as well. I have no idea if that is the case. I see the “processor” with the SIM card underneath. There are numbers on top of the plastic processor box that are different from the one replaced. Am I jumping at straws or the old one, 03Z06 77511, is different from the new one, 03Z06 21091 and not compatible? As you can see, I don’t know the proper id nomenclature. How about the old board numbers, 07100 00101, vs 007100 001YL. Can someone tell me if chasing rabbits or are these the equivalent components and I’m simply not smart enough to fly this thing again?