Play Along to learn the code to unlock the cache
1 1 5 5 6 6 5
4 4 3 3 2 2 1
5 5 4 4 3 3 2
5 5 4 4 3 3 2
1 1 5 5 6 6 5
A A B B C C D
The letters A, B, C, D equate to the numbers on the instrument. By solving the remainder of the tune, you will have the code to unlock the cache.
A tune that we all learned in our youth.