Place the MMA7361 on the desk and tighten it, keep it actionless.
I measured the X, Y, Z voltage. They are 1.63V, 1.71V, 2.25V
VDD is 3.3V
So, Ax(acc of X) = (1.63-1.65)/0.8 = -0.025
Ay(acc of Y) = 0.075
Az = 0.75
But (-0.025)^2 + 0.075^2 + 0.75^2 <> 1