Hello, appreciate any advice on the this. I have 3 keys for my 2004 XJ6 X350 model, all have lost their radio sychronisation so I cannot remotely unlock the car. Earlier today I was able to use one set of keys to manually unlock the car and start it. Since then, I can now longer even manually unlock the car. The key just seems to turn in the lock (maybe the heat at the moment is a factor?). I have replaced the batteries in all 3 sets of keys that I have, however that has not helped. Anything else I can try? Anyone who is good to contact regarding this? Thanks in advance! Paul