Ive been having this same problem as well, yesterday the keyfob was having none of it and wouldnt light up had to open up the fob take out the pcb and manually had to create the circuit with a small bit of metal to get it to work, it looks as if a switch or something has fallen off from where the small plastic button presses down but there was nothing loose in there.
And sods law i couldnt find my other key to check