Misty Davis

I have a 2015 Chevy Silverado 1500 4x4, I tried to park the truck and it would not go in to park, i left in neutral and set the emergency brake. I unhooked the battery cable over night went out side this morning and while the battery cable was unhooked i was able to get the truck in park. I drove the truck to work and it wouldnt go back in park, i got out unhooked cable and it went into park again. What could this be and how much of a hassle to fix at home? Thanks for the help