It's frustrating to find that your BMW does not unlock when the button on the integrated remote key is pressed. While the alarm may be disarmed by opening the door with the key in the traditional manner and the vehicle may be started, a non-functional remote is an inconvenience. BMW does not repair or service keys, but dealers will order a new key, which can be expensive, and then have it cut especially for your car. It may be just a dead battery. Regardless, you will have to get the remote open first. A few simple tricks may allow you to save your seemingly dead integrated remote BMW key from the trash.
Verify that the key's battery needs to be replaced by driving around for an hour using the presumed defective key. The battery in the integrated remote is rechargeable and charges in the ignition when the car is on. Often, a key will lose its charge when it has been sitting unused for an extended amount of time. Attempt to lock the doors with the remote button on the key after trying to recharge it. Proceed to the next step if this has not solved the problem.
Heat the key uniformly using a hair dryer on medium while wearing protective leather gloves and safety glasses, if you do not have an older model key that you may simply unscrew. The two halves of the key are glued together with a urethane adhesive that must be softened before attempting separation. Heat the key to the point where it is uncomfortable to touch but not where it could cause a burn. Adjust the position of the key constantly so that it is heated evenly without any hot spots.
Hold it by the metal key portion using needle-nose vice grips. Don't use too much force and scratch the key's finish. Insert the dull utility blade between the base of the metallic portion of the key and one of the plastic side casings. Pry the casing outward slightly using the dull knife blade until a small gap forms around the entire key.
Leave the blade in place while you remove the vice grips. Use several small flat-bladed screwdrivers to pry around the periphery of the key to slowly tear the adhesive bond on the case. If the key has cooled and the case is no longer separating, re-heat with the blow dryer as necessary. The adhesive should turn to a gum-like consistency above 125 degrees Fahrenheit.
Remove the rechargeable battery once the case is successfully opened. The battery is a three volt Panasonic VL2020 cell that may be found at online vendors and specialty battery stores. Reinstall the replacement battery. Prior to re-sealing the key, test it to ensure that you replaced the battery properly and it's working. Additional re-heating of the key should soften the old adhesive to the point that the key can simply be clamped together and let cool to set.
