Hi Mike, I have a 2018 XC60 and checking through the handbook, as Paul says above, there is no mention of reprogramming the remote key just changing the batteries. There is reference to having a new remote key programmed to the car at a dealer, the car can apparently support 12 individual keys! If the batteries are correct and in the right way and if you have your car serviced at a Volvo Authorised service centre then you should have Volvo Assistance cover, could be worth a call. Tel: 0800 777 116.
Good luck
