it appears that in your for loop you are doing 4 shifts
for (int c = 0; c <= 3; c++)
there should only be three bytes, because it is a 24 bit device
remember that for loops run zero, then 1, then 2, etc.
it should be:
for (int c = 0; c <= 2; c++)
or
for (int c = 0; c < 3; c++)
I've made this painful mistake far too many times