There should be no pairing. If you are sure, that the Beo4 is working, it's most likely, that the remote receiver is not longer working in the BeoSound 2000. If the latter is the case, I made this kit: https://www.beoparts-shop.com/product/beosound-century-ir-remote-control-pcb-service-kit/ Martin

Hi, first make sure the Beo4 is working. If you don't have another B&O product to confirm it works, you can use the camera on a phone to record while pressing some buttons. The video will show the infrared pulses that you can't see with the naked eye. On the Beo4 the lens is the small plastic piece on the edge above the display screen.  If your camera has picked up the pulses you know the remote is working. If the remote is working you need to make sure the BS2000 has remote operation enabled. With the unit in standby, push the standby button (red dot), then sound, 1, store.  You should see a 1 flash in the display. This will enable remote operation. If the remote is working properly and remote operation is enabled but the system still doesn't respond you will need the kit. Dillen is the best and beoparts is the best place to source the proper parts.