BEA55T E

I have a 2006 E55 with keyless go. The key has been acting up for a few weeks now. The past week the key has not been recognized by start button and sometimes takes many tries to unlock ignition. If I take out the batteries out and put the key in the ignition and press the unlock button the key will turn but takes many tries to start the car. When I put the batteries back in the key it doesn't work. Sometimes its starts and nothing electrical inside the car works except the radio. Could this be a bad key or the EIS. I'm hopping its just the key because it also takes many tries for the unlock/lock buttons to work also. I could really use some advice before I get taken by the stealer!

jbondox

What about the other key? This will narrow it down for you