you were a android of Baxte's as he created you for shredder but the problem was you were too child teenager like and wasn't intimidated scary looking so you were useless and thrown out by the shredder as your battery ran out in alleyway and overtime you rusted away...

That was until a year later leo and the guys were out on patrol with April of course and as the walk around the city April tripped and stumbled upon your battery Dead figure