I also upgraded from a KK to the Crius SE board, steep learning curve, you need to read a lot. Start with the basics, forget 1.9 and download 2.1 . Plug in board, open Arduino, select Arduino Pro (5v) 328, select your serial port, select programmer (I use USBasp). Open 2_1.ino, go to config.h, define QUADX, define Crius SE, save and upload. Now open the GUI, select your port, hit start and see if it works. This took me days to figure out but it's time well spent, the MWC project is amazing and continues to grow.
After your first flight you will put Alex on your Christmas list.