Turnigy Plush 60A
 

I received a PNP plane from a friend. It's flyable, but my throttle is having an issue. My motor won't engage and spin until throttle stick is at 50%. Thought it was a setting in my Tx, couldn't find anything. Swapped Rx and Tx and same result. ESC programming issue? Everything else is perfect, just never seen this before. Please HELP!!!