Your idea is simple. Make an explosive puppet, then set it to explode when it reaches a certain speed, the set speed of the NANN-E. You're going to need a few supplies, namely, an eye of newt, a dragon's claw, a figment of imagination, and a whole bunch of glycerol. Luckily, you have all except the glycerol. Unluckily, the fastest way to get it, is from a bunch of whisky. Which you're going to have to get from Nikola the Bear's wagon. She is not going to like that.
Now, how did your father let NANN-E stay on the property, NANN-E simply fled the scene quickly because it was built for speed in the event that you would need someone to quickly save you. Your father was intimate about that detail, he wanted it to be extremely fast and be able to fight whatever (or whoever) was trying to hurt you. The hubris of us all.