Hello everyone. I want to let everyone know that both my BMW keys have stopped working electronically and when I went to my local dealership for help, they said that I would have to replace both of them with new ones for around $300.00 per key. I asked if I could replace the batteries but they said no because it is embedded into the housing. So, before spending $600.00 for new keys, I decided to use my engineering background and disassemble the keys one step at at time. What I found is that there is a rechargeable battery inside that can be replaced. It is slightly saudered to the key which can be pried off gently with a small knife. I went to "Batteries Plus" and purchase two replacement battery's for $15.00 per battery. I replaced the batteries and used a little glue to secure the key together and it's like having brand new keys again.

I hope this helps any and all BMW owners when their keys stop working due to the battery and you don't want to spend an arm and a leg to replace them.