A tiny rock fell into one of Phoebe's motors and jammed it up. You can find these motors on Amazon for 20 to 30 dollars. You can either get a genuine DJI part, or a TAOKE 1504S which is the part DJI buys.
If you have soldering skills, it is not hard to do. The wires slide sideways into notches in the board and are very easy to put in.