All of a sudden my car boot stopped opening from the button on the key, one minute it would open it and the next it wouldn't, also the button on the dash no longer works to open the boot. I can open the boot manually by inserting the key and when I press the button on the key I can hear something inside the mechanism of the boot moving but it doesn't open. I suspected it could have been the batteries in my key so replaced these but still have the same problem. Can you advise what might be wrong and what I can do to try to fix it?