The "normal" startup is 3 swash pitch-pumps: up, down, up and then to the position of the collective stick.
The 15 pitch-pumps indicate:
A) Bad accelerometers (failed their start up test)
B) The gyro is not close to level when it is powered up.
"A" can happen anytime the gyro has been knocked around, dropped or crashed. It is permanent and cannot be fixed. If it is new, talk to the place you bought it about a replacement.
"B" can happen if the heli is tilted more than about 30* from level at power up. That includes not attached to the gyro mount, sitting on the bench or dangling from the wires when it is powered up.
BTW: "Level" is determined by the "orientation" setting in the MSH Setup App.
EG: If you mistakenly chose an orientation of "label down" instead of "label up", then you will always get 15 pitch-pumps on power-up.
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