Volvo S80 2001 Auto
 

This is my first time posting.
The back central locking and boot are not opening. The petrol gauge is sitting at zero and the message on the dashboard states the airbag service urgent.
I called the breakdown service and they checked all the fuses and appeared fine. He disconnected the battery and all was working fine for several days, but the same thing happened again.
any suggestions

Is this a recently acquired vehicle or something you've been driving for a while?

Car battery strong?

Maybe one of those "magic rest procedures" involving fob presses/door lock/unlock actuation and ignition switching exists.

Volvo specific code reading could reveal a bad DMM or other involved node.

Had car for 23 years. Battery new 1 year old. I have for the last 5 years opened the car with key as alarm gave up many years ago. Tried FOB unlocks front doors but not back doors or boot.