2006 156 JTS - key remote doesn't unlock car/boot and doesn't start car
Yeah... pretty much what the title is.
Went to pick up something from the shops, car started fine, drove over there, parked, grabbed my stuff, 5 minutes later came out and the remote wouldn't open the car. Unlocked it manually, car wouldn't start, no sound, no activity, no warning lights, nothing.
Went to the key cutter people inside the centre and the guy tested the key and said the battery was fine, checked if it was transmitting when the boot and door unlock buttons were pressed, that was fine too so he didn't replace the battery.
Got the spare key, tried that, same thing.
Central locking doesn't work either with the key or with pressing the locks inside, each door has to be locked individually.
The key previously stopped working once but that was only the unlocking function that stopped. Just locked the car manually, drove it home fine, then it started working magically the next day.
Have read a couple of things like replacing fuses and disconnecting the battery for half an hour to see if it resets the transponder, would any of this work? Also have read that I might have to get the key re-programmed for the immobiliser but would that apply as the spare didn't work as well?
Any help would be great, thanks in advance.