At the main menu, enter the password option and type in:

3NKFZ8 - level 1
9MD1WV - level 2
XTN4F7 - level 3
5BVPL2 - level 4
9D6F0S - level 5
TSCNB4 - level 6
CSJTQZ - level 7
BNPXZ9 -level 8
GH9MR - level 9 (End)