Since the seatback eventually goes back with repeated pressing of the button, it's probably not the cable. The seat relys on potentiometers in each motor for memory function. It sounds like a problem with the backrest potentiometer or wiring. Could also be as simple as resetting the end limits for the seat. This can be done through the diagnostic link under the hood either manually, or with a scan tool. The manual method is difficult and requires many steps. With the dealers scan tool, it's quick and easy. Plug your diagnostic wire at the socket under the hood into B-6 and read fault codes for the seat, then repost.