My key fob will not open the car or turn off the alarm. I press the button and nothing happens. The red alarm light on the dash is flashing. I have replaced the battery in the fob, no joy. I put a fan heater into the car and left it there for a couple of hours, still no joy. If I open the door with the key manually the alarm goes off. I had a new battery in the car last month and it's not that. Anyone got any advice please??