This is personal experience but I have found out that if it is dead for long period of time, or you take the old battery out and don't immediately put a new battery in, it may/will erase the link with you vehicle. I hate to say this but my suggestion is to take it to the dealer and they should fix it for around $50. They say it takes them 30 minutes to program. I think that’s BS but I really don't know. I wouldn't pay more than $75 for the issue if they want more than $50. Keep searching around if they do indeed want more than $50. I will look deeper into this and if I find anything I will follow up.