feelThere Phenom 100 YD problem

Hi all,

Been a while since I posted here. Long time no see, hey.

I've been re-acquainting myself with the feelThere Phenom 100.

(Now that I have a laptop with more than enough grunt.)

I was taking the Intro flight, per the manual.

All was going well. Took off, AP did the left turn nicely.

Began the After Take-Off Checklist.

Step 4: Yaw Dampener.... ON.

I clicked the YD button, and that's when it went crazy.

It flipped straight into a dive, with the annunciator calling something about the autopilot.

Then seconds later, it nosed into the ground.

Can anyone suggest what I missed, or a remedy for this poorly behaving little Phenom?

Thanks