One of my key fobs stopped working so I followed the advice on here and fitted a new CR1616 battery, but still nothing. The little red light doesn't even light up when you push a button. I tested the battery with a multimeter and it's showing 3V and I've checked it's the right way round. Do the electronics in the fobs pack up, or have I boobed in buying a cheap battery and perhaps they only work with quality ones? Does that really make a difference?