I have a FOB key that came with the vehicule that I purchase. The emergency key works to open the door and the car will start with the FOB but the FOB will not lock or open the doors remotely despite changing the batteries. I would like to know if it is possible to reprogram that key or at least try before I invest in purchasing a new key.

 

My 2015 remote range got shorter and shorter, then stopped working, then I got a tire pressure system warning. (all tires were good, sensors tested ok) . The problem was the antenna for the remote/tire sensors. Replaced with a used part (same part is used for multiple volvos/multiple years), remote works again and no tire pressure system warning.
The antenna is located above the headliner in the very center of the car. google Volvo 30659715

As far as "reprogramming" - the CEM was programmed to accept the signal from that remote - unless there is a problem with your CEM it should still accept the signal. Does your remote use 2 cr2450 batteries? Installed in a weird way with paper/plastic between them?