Problem with uploading LUFA MassStorage .hex file to Leonardo

I have been trying to make my Leonardo board to work as a USB device. So I started with compiling the open source LUFA USB library demo "MassStorage" for the Leonardo board settings. Since I'm using Mac OS, I downloaded the "AVR Tools" software to upload the hex file to the board(I didn't want to use the ISP protocol to flash. Because it is not possible to remove the chip from the board to make the correct ISP circuit connection). Anyway I was managed to flash the board. But afterwards it is not detectable by the computer. The serial port is not detectable. This proves it flashed something. Afterwards I flashed it again with the original bootloader file and it was identified as before. I'm a beginner to Arduino programming and forgive me if I'm asking elementary question. What am I doing wrong? Can someone provide me a .hex file of MassStorage demo for Leonardo board(only if u have)? Because Im not sure if I compiled the file correctly too.