I was happy to get my MM in the air for it's first flight (I read the manual entirely and read a lot of forums on the MM before attempting the first flight) which is my first in a drone (flew RC helos)! I was dismayed that I got a "motor speed" error about 30 seconds into the first flight with the instruction to land and change the propellers! I did that on the lower left motor using the correct replacement blades and attempted to launch again. The drone lifted up off the pad and immediately slid left backwards and down into the grass (I was launching off of a helo pad) converting from a drone to a lawn mower (complete with cut grass stains on the main body) I quickly shut down and was shocked to see that the left rear motor was missing a propeller (which is why it settled to the left rear from loss of lift)! I must not have secured the screw as well as I should (the other propeller was fine). Out came another propeller set from the DJI Fly More package. This time the drone lifted to a hover then followed my flight commands before another "motor speed" error demanded a return to the shop for another set of propellers...this time it was the left forward set. I changed propellers and launched again... another motor speed error! This time it was the right rear motor. Another set of propellers changed! That was it...the fourth flgiht went smoothly with no more "motor speed" warnings. I came home and binged on forums for "motor speed" errors. I did all the firmware updates before the first flight (as prompted by the controller) so I am not sure if it was a software issue. I did see a Youtube video that suggested the problem came from improper storage of the propellers in the Fly More case (nice case). According to the label in the case, the propellers need to be stored in an "I" pattern directly across the body. I was storing them in the "X" pattern which apparently can cause the blade to warp out of shape and thus lead to a "motor speed" error. I have a new set of blades on order so I will be ready for my next outing...and I am carefully storing the blades in the "I" position now. I hope this fixes the problem!