Just FYI-- I had something happen yesterday while debugging that is very likely to happen to others. When plugging in the mini-USB plug into the FRDM-KL25 board (I unplug/plug often while debugging), I accidentally missed and the plug hit the lower part of the FRDM-TFC board. It caused a short and a little smoke!
Turns out I likely shorted the underside of the ground and Vbattery terminals to the servo. Thankfully I pulled it away fast enough to not cause damage.
I've added some electrical tape on the underside of the FRDM-TFC board just in case in that area.
Here's a pic highlighting the possible short you could do: