My transponder key will not manually unlock my driver's door. I can manually lock it and the remote works properly. I can manually lock and unlock the passenger door and rear gate. It had this same problem when I bought it new on the lot and when I had them look up the records, all they could tell me was "an ECU had to be replaced. Any ideas what the problems might be and/or what parts I may need? The only thing I've been able to find on the net thus far is a lock actuator. How hard would it be for a total novice to replace this? Thanks.